diff --git a/ChangeLog.md b/ChangeLog.md
index be635c1..2f31e92 100644
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -1,5 +1,12 @@
 # Peplum ChangeLog
 
+## Unreleased
+
+**Released: WiP**
+
+- Added the ability to view the source of a PEP.
+  ([#17](https://github.com/davep/peplum/pull/17))
+
 ## v0.2.0
 
 **Released: 2025-01-27**
diff --git a/README.md b/README.md
index 8d391fc..54761a1 100644
--- a/README.md
+++ b/README.md
@@ -50,6 +50,7 @@ Expanding for the common locations, the files normally created are:
 
 - `~/.config/peplum/configuration.json` -- The configuration file.
 - `~/.local/share/peplum/*.json` -- The locally-held PEP data.
+- `~/.local/share/peplum/cache/*.rst` -- The locally-cached PEP source files.
 
 ## Getting help
 
diff --git a/src/peplum/app/commands/__init__.py b/src/peplum/app/commands/__init__.py
index 92073b8..d964eea 100644
--- a/src/peplum/app/commands/__init__.py
+++ b/src/peplum/app/commands/__init__.py
@@ -25,6 +25,7 @@
     Quit,
     RedownloadPEPs,
     TogglePEPDetails,
+    ViewPEP,
 )
 from .navigation_sorting import (
     ToggleAuthorsSortOrder,
@@ -59,6 +60,7 @@
     "TogglePythonVersionsSortOrder",
     "ToggleStatusesSortOrder",
     "ToggleTypesSortOrder",
+    "ViewPEP",
 ]
 
 ### __init__.py ends here
diff --git a/src/peplum/app/commands/main.py b/src/peplum/app/commands/main.py
index 5d121db..cdf007f 100644
--- a/src/peplum/app/commands/main.py
+++ b/src/peplum/app/commands/main.py
@@ -61,4 +61,12 @@ class TogglePEPDetails(Command):
     BINDING_KEY = "f3"
 
 
+##############################################################################
+class ViewPEP(Command):
+    """View the source of the currently-highlighted PEP"""
+
+    FOOTER_TEXT = "View"
+    BINDING_KEY = "f4"
+
+
 ### main.py ends here
diff --git a/src/peplum/app/data/__init__.py b/src/peplum/app/data/__init__.py
index 333c1b9..e65a2c7 100644
--- a/src/peplum/app/data/__init__.py
+++ b/src/peplum/app/data/__init__.py
@@ -8,6 +8,7 @@
     save_configuration,
     update_configuration,
 )
+from .locations import cache_dir
 from .notes import Notes
 from .pep import PEP, PEPStatus, PEPType, PostHistory
 from .peps import (
@@ -28,17 +29,18 @@
 ##############################################################################
 # Exports.
 __all__ = [
-    "pep_data",
     "AuthorCount",
+    "cache_dir",
     "Configuration",
     "Containing",
     "load_configuration",
     "Notes",
     "PEP",
-    "PEPStatus",
-    "PEPType",
+    "pep_data",
     "PEPCount",
     "PEPs",
+    "PEPStatus",
+    "PEPType",
     "PostHistory",
     "PythonVersionCount",
     "save_configuration",
diff --git a/src/peplum/app/data/locations.py b/src/peplum/app/data/locations.py
index ae4c6cb..7d6deed 100644
--- a/src/peplum/app/data/locations.py
+++ b/src/peplum/app/data/locations.py
@@ -41,6 +41,21 @@ def data_dir() -> Path:
     return _app_dir(xdg_data_home())
 
 
+##############################################################################
+def cache_dir() -> Path:
+    """The path to the cache directory for the application.
+
+    Returns:
+        The path to the cache directory for the application.
+
+    Note:
+        If the directory doesn't exist, it will be created as a side-effect
+        of calling this function.
+    """
+    (cache := data_dir() / "cache").mkdir(parents=True, exist_ok=True)
+    return cache
+
+
 ##############################################################################
 def config_dir() -> Path:
     """The path to the configuration directory for the application.
diff --git a/src/peplum/app/peplum.py b/src/peplum/app/peplum.py
index 131d49d..4a1a7ef 100644
--- a/src/peplum/app/peplum.py
+++ b/src/peplum/app/peplum.py
@@ -33,6 +33,11 @@ class Peplum(App[None]):
         }
     }
 
+    /* Make the LoadingIndicator look less like it was just slapped on. */
+    LoadingIndicator {
+        background: transparent;
+    }
+
     /* Remove cruft from the Header. */
     Header {
         /* The header icon is ugly and pointless. Remove it. */
diff --git a/src/peplum/app/providers/main.py b/src/peplum/app/providers/main.py
index fc88c25..1736c0a 100644
--- a/src/peplum/app/providers/main.py
+++ b/src/peplum/app/providers/main.py
@@ -24,6 +24,7 @@
     TogglePythonVersionsSortOrder,
     ToggleStatusesSortOrder,
     ToggleTypesSortOrder,
+    ViewPEP,
 )
 from .commands_provider import CommandHits, CommandsProvider
 
@@ -59,6 +60,7 @@ def commands(self) -> CommandHits:
         yield TogglePythonVersionsSortOrder()
         yield ToggleStatusesSortOrder()
         yield ToggleTypesSortOrder()
+        yield ViewPEP()
 
 
 ### main.py ends here
diff --git a/src/peplum/app/screens/main.py b/src/peplum/app/screens/main.py
index a3a6bf9..efdf61d 100644
--- a/src/peplum/app/screens/main.py
+++ b/src/peplum/app/screens/main.py
@@ -44,6 +44,7 @@
     TogglePythonVersionsSortOrder,
     ToggleStatusesSortOrder,
     ToggleTypesSortOrder,
+    ViewPEP,
 )
 from ..data import (
     PEP,
@@ -78,6 +79,7 @@
 from ..widgets import Navigation, PEPDetails, PEPsView
 from .help import HelpScreen
 from .notes_editor import NotesEditor
+from .pep_viewer import PEPViewer
 from .search_input import SearchInput
 
 
@@ -148,6 +150,7 @@ class Main(Screen[None]):
         Help,
         EditNotes,
         TogglePEPDetails,
+        ViewPEP,
         Quit,
         RedownloadPEPs,
         # Everything else.
@@ -529,5 +532,16 @@ async def action_edit_notes_command(self) -> None:
                 self.all_peps.patch_pep(self.selected_pep.annotate(notes=notes))
             )
 
+    @on(ViewPEP)
+    def action_view_pep_command(self) -> None:
+        """View the currently-highlighted PEP's source."""
+        if self.selected_pep is None:
+            self.notify("Highlight a PEP to view it.", severity="warning")
+            return
+        if self.selected_pep.number == 0:
+            self.notify("PEP0 has no source to view.", severity="warning")
+            return
+        self.app.push_screen(PEPViewer(self.selected_pep))
+
 
 ### main.py ends here
diff --git a/src/peplum/app/screens/pep_viewer.py b/src/peplum/app/screens/pep_viewer.py
new file mode 100644
index 0000000..3ef6930
--- /dev/null
+++ b/src/peplum/app/screens/pep_viewer.py
@@ -0,0 +1,151 @@
+"""A dialog for viewing the text of a PEP."""
+
+##############################################################################
+# Python imports.
+from pathlib import Path
+
+##############################################################################
+# Textual imports.
+from textual import on, work
+from textual.app import ComposeResult
+from textual.containers import Horizontal, Vertical
+from textual.screen import ModalScreen
+from textual.widgets import Button, TextArea
+
+##############################################################################
+# Local imports.
+from ...peps import API
+from ..data import PEP, cache_dir
+from ..widgets import TextViewer
+
+
+##############################################################################
+class PEPViewer(ModalScreen[None]):
+    """A modal screen for viewing a PEP's source."""
+
+    CSS = """
+    PEPViewer {
+        align: center middle;
+
+        &> Vertical {
+            width: 80%;
+            height: 80%;
+            max-height: 80%;
+            background: $panel;
+            border: solid $border;
+        }
+
+        TextViewer {
+            color: $text-muted;
+            height: 1fr;
+            scrollbar-background: $panel;
+            scrollbar-background-hover: $panel;
+            scrollbar-background-active: $panel;
+            &:focus {
+                color: $text;
+            }
+        }
+
+        #buttons {
+            height: auto;
+            align-horizontal: right;
+            border-top: solid $border;
+        }
+
+        Button {
+            margin-right: 1;
+        }
+    }
+    """
+
+    BINDINGS = [("escape", "close"), ("ctrl+r", "refresh"), ("ctrl+c", "copy")]
+
+    def __init__(self, pep: PEP) -> None:
+        """Initialise the dialog.
+
+        Args:
+            pep: The PEP to view.
+        """
+        super().__init__()
+        self._pep = pep
+        """The PEP to view."""
+
+    def compose(self) -> ComposeResult:
+        """Compose the dialog's content."""
+        key_colour = (
+            "dim" if self.app.current_theme is None else self.app.current_theme.accent
+        )
+        with Vertical() as dialog:
+            dialog.border_title = f"PEP{self._pep.number}"
+            yield TextViewer()
+            with Horizontal(id="buttons"):
+                yield Button(f"Copy [{key_colour}]\\[^c][/]", id="copy")
+                yield Button(f"Refresh [{key_colour}]\\[^r][/]", id="refresh")
+                yield Button(f"Close [{key_colour}]\\[Esc][/]", id="close")
+
+    @property
+    def _cache_name(self) -> Path:
+        """The name of the file that is the cached version of the PEP source."""
+        return cache_dir() / API.pep_file(self._pep.number)
+
+    @work
+    async def _download_text(self) -> None:
+        """Download the text of the PEP.
+
+        Notes:
+            Once downloaded a local copy will be saved. Subsequently, when
+            attempting to download the PEP, this local copy will be used
+            instead.
+        """
+        (text := self.query_one(TextViewer)).loading = True
+        pep_source = ""
+
+        if self._cache_name.exists():
+            try:
+                pep_source = self._cache_name.read_text(encoding="utf-8")
+            except IOError:
+                pass
+
+        if not pep_source:
+            try:
+                self._cache_name.write_text(
+                    pep_source := await API().get_pep(self._pep.number),
+                    encoding="utf-8",
+                )
+            except IOError:
+                pass
+            except API.RequestError as error:
+                pep_source = "Error downloading PEP source"
+                self.notify(
+                    str(error), title="Error downloading PEP source", severity="error"
+                )
+
+        text.text = pep_source
+        text.loading = False
+        self.set_focus(text)
+
+    def on_mount(self) -> None:
+        """Populate the dialog once the DOM is ready."""
+        self._download_text()
+
+    @on(Button.Pressed, "#close")
+    def action_close(self) -> None:
+        """Close the dialog."""
+        self.dismiss(None)
+
+    @on(Button.Pressed, "#refresh")
+    def action_refresh(self) -> None:
+        """Refresh the PEP source."""
+        try:
+            self._cache_name.unlink(missing_ok=True)
+        except IOError:
+            pass
+        self._download_text()
+
+    @on(Button.Pressed, "#copy")
+    async def action_copy(self) -> None:
+        """Copy PEP text to the clipboard."""
+        await self.query_one(TextArea).run_action("copy")
+
+
+### pep_viewer.py ends here
diff --git a/src/peplum/app/widgets/__init__.py b/src/peplum/app/widgets/__init__.py
index 913221b..a0d2c6e 100644
--- a/src/peplum/app/widgets/__init__.py
+++ b/src/peplum/app/widgets/__init__.py
@@ -5,10 +5,11 @@
 from .navigation import Navigation
 from .pep_details import PEPDetails
 from .peps_view import PEPsView
+from .text_viewer import TextViewer
 
 ##############################################################################
 # Exports.
-__all__ = ["Navigation", "PEPDetails", "PEPsView"]
+__all__ = ["Navigation", "PEPDetails", "PEPsView", "TextViewer"]
 
 
 ### __init__.py ends here
diff --git a/src/peplum/app/widgets/text_viewer.py b/src/peplum/app/widgets/text_viewer.py
new file mode 100644
index 0000000..1bc3ff2
--- /dev/null
+++ b/src/peplum/app/widgets/text_viewer.py
@@ -0,0 +1,82 @@
+"""A widget for viewing text."""
+
+##############################################################################
+# Textual imports.
+from textual.widgets import TextArea
+
+
+##############################################################################
+class TextViewer(TextArea):
+    """A widget for viewing text."""
+
+    DEFAULT_CSS = """
+    TextViewer {
+        background: transparent;
+        border: none;
+        &:focus {
+            border: none;
+        }
+        & > .text-area--cursor-line {
+           background: transparent;
+        }
+    }
+    """
+
+    BINDINGS = [
+        ("<", "cursor_line_start"),
+        (">", "cursor_line_end"),
+        ("c, C", "copy"),
+    ]
+
+    def __init__(
+        self,
+        text: str = "",
+        *,
+        name: str | None = None,
+        id: str | None = None,
+        classes: str | None = None,
+        disabled: bool = False,
+    ) -> None:
+        """Initialise the object.
+
+        Args:
+            text: The text to view.
+            name: The name of the TextViewer.
+            id: The ID of the TextViewer in the DOM.
+            classes: The CSS classes of the TextViewer.
+            disabled: Whether the TextViewer is disabled or not.
+        """
+        super().__init__(
+            text,
+            read_only=True,
+            name=name,
+            id=id,
+            classes=classes,
+            disabled=disabled,
+        )
+
+    def action_copy(self) -> None:
+        """Action for copying text to the clipboard."""
+        if for_clipboard := self.selected_text:
+            self.notify("Selected text copied to the clipboard.")
+        else:
+            for_clipboard = self.text
+            self.notify("All text copied to the clipboard.")
+        self.app.copy_to_clipboard(for_clipboard)
+
+    def action_cursor_line_start(self, select: bool = False) -> None:
+        """Add a slightly smarter use of going 'home'."""
+        if self.cursor_at_start_of_line:
+            self.move_cursor(self.document.start, select=select)
+        else:
+            super().action_cursor_line_start(select)
+
+    def action_cursor_line_end(self, select: bool = False) -> None:
+        """Add a slightly smarter use of going 'end'."""
+        if self.cursor_at_end_of_line:
+            self.move_cursor(self.document.end, select=select)
+        else:
+            super().action_cursor_line_end(select)
+
+
+### text_viewer.py ends here
diff --git a/src/peplum/peps/api.py b/src/peplum/peps/api.py
index 3f74066..5eb7fdd 100644
--- a/src/peplum/peps/api.py
+++ b/src/peplum/peps/api.py
@@ -2,12 +2,13 @@
 
 ##############################################################################
 # Python imports.
+from pathlib import Path
 from ssl import SSLCertVerificationError
 from typing import Any, Final
 
 ##############################################################################
 # HTTPX imports.
-from httpx import AsyncClient, HTTPStatusError, RequestError
+from httpx import AsyncClient, HTTPStatusError, RequestError, Response
 
 
 ##############################################################################
@@ -38,19 +39,20 @@ def _client(self) -> AsyncClient:
             self._client_ = AsyncClient()
         return self._client_
 
-    async def get_peps(self) -> dict[int, dict[str, Any]]:
-        """Download a fresh list of all known PEPs.
+    async def _get(self, url: str) -> Response:
+        """Make a GET request.
+
+        Args:
+            url: The URL to make the request of.
 
         Returns:
-            The PEP JSON data.
+            The response.
 
         Raises:
-            RequestError: If there was a problem getting the PEPS.
+            RequestError: If there was some sort of error.
         """
         try:
-            response = await self._client.get(
-                self._URL, headers={"user-agent": self.AGENT}
-            )
+            response = await self._client.get(url, headers={"user-agent": self.AGENT})
         except (RequestError, SSLCertVerificationError) as error:
             raise self.RequestError(str(error)) from None
 
@@ -59,10 +61,60 @@ async def get_peps(self) -> dict[int, dict[str, Any]]:
         except HTTPStatusError as error:
             raise self.RequestError(str(error)) from None
 
-        if isinstance(raw_data := response.json(), dict):
-            return raw_data
+        return response
+
+    async def get_peps(self) -> dict[int, dict[str, Any]]:
+        """Download a fresh list of all known PEPs.
+
+        Returns:
+            The PEP JSON data.
 
+        Raises:
+            RequestError: If there was a problem getting the PEPS.
+        """
+        if isinstance(
+            raw_data := (
+                await self._get("https://peps.python.org/api/peps.json")
+            ).json(),
+            dict,
+        ):
+            return raw_data
         raise RequestError("Unexpected data received from the PEP API")
 
+    @staticmethod
+    def pep_file(pep: int) -> Path:
+        """Generate the name of the source file of a PEP.
+
+        Args:
+            pep: The number of the PEP.
+
+        Returns:
+            The name of the source file for that PEP.
+        """
+        return Path(f"pep-{pep:04}.rst")
+
+    @classmethod
+    def pep_url(cls, pep: int) -> str:
+        """Generate the URL for the source of a PEP.
+
+        Args:
+            pep: The number of the PEP.
+
+        Returns:
+            The URL for the source of the PEP.
+        """
+        return f"https://raw.githubusercontent.com/python/peps/refs/heads/main/peps/{cls.pep_file(pep)}"
+
+    async def get_pep(self, pep: int) -> str:
+        """Download the text of a given PEP.
+
+        Args:
+            pep: The number of the PEP to download.
+
+        Returns:
+            The text for the PEP.
+        """
+        return (await self._get(self.pep_url(pep))).text
+
 
 ### api.py ends here