diff --git a/NAMESPACE b/NAMESPACE
index f8c8710..358d1a1 100644
--- a/NAMESPACE
+++ b/NAMESPACE
@@ -2,6 +2,7 @@
 
 export(add_benchmark_tr_score)
 export(add_thresholds_transition_risk)
+export(add_transition_risk_category)
 export(add_transition_risk_score)
 export(toy_all_uuids_scenario_sectors)
 importFrom(dplyr,.data)
@@ -17,6 +18,7 @@ importFrom(readr,read_csv)
 importFrom(rlang,abort)
 importFrom(stats,quantile)
 importFrom(tibble,tribble)
+importFrom(tiltIndicator,categorize_risk)
 importFrom(tiltIndicator,epa_compute_profile_ranking)
 importFrom(tiltIndicator,spa_compute_profile_ranking)
 importFrom(tiltToyData,toy_emissions_profile_products_ecoinvent)
diff --git a/R/add_transition_risk_category.R b/R/add_transition_risk_category.R
new file mode 100644
index 0000000..619f9d6
--- /dev/null
+++ b/R/add_transition_risk_category.R
@@ -0,0 +1,43 @@
+#' Adds transition risk categories for transition risk scores
+#'
+#' @param data A dataframe
+#'
+#' @keywords internal
+#' @return A dataframe.
+#'
+#' @export
+#'
+#' @examples
+#' library(tiltToyData)
+#' library(readr)
+#' library(dplyr)
+#' options(readr.show_col_types = FALSE)
+#'
+#' emissions_profile_products <- read_csv(toy_emissions_profile_products_ecoinvent())
+#' all_uuids_scenario_sectors <- read_csv(toy_all_uuids_scenario_sectors())
+#' scenarios <- read_csv(toy_sector_profile_any_scenarios())
+#'
+#' transition_risk_thresholds <- add_thresholds_transition_risk(
+#'   emissions_profile_products,
+#'   all_uuids_scenario_sectors,
+#'   scenarios
+#' )
+#'
+#' output <- add_transition_risk_category(transition_risk_thresholds)
+#' output
+add_transition_risk_category <- function(data) {
+  check_crucial_cols(data, c(
+    col_transition_risk_score(), col_tr_low_threshold(),
+    col_tr_high_threshold()
+  ))
+
+  mutate(data, transition_risk_category = ifelse(
+    is.na(.data[[col_transition_risk_score()]]),
+    NA,
+    categorize_risk(
+      .data[[col_transition_risk_score()]],
+      .data[[col_tr_low_threshold()]],
+      .data[[col_tr_high_threshold()]]
+    )
+  ))
+}
diff --git a/R/col-transition_risk_profile.R b/R/col-transition_risk_profile.R
index 56382ea..c3a9b28 100644
--- a/R/col-transition_risk_profile.R
+++ b/R/col-transition_risk_profile.R
@@ -33,3 +33,15 @@ col_targets <- function() {
 col_ranking <- function() {
   "profile_ranking"
 }
+
+col_transition_risk_score <- function() {
+  "transition_risk_score"
+}
+
+col_tr_low_threshold <- function() {
+  "transition_risk_low_threshold"
+}
+
+col_tr_high_threshold <- function() {
+  "transition_risk_high_threshold"
+}
diff --git a/R/tiltTransitionRisk-package.R b/R/tiltTransitionRisk-package.R
index fbee90a..212b01e 100644
--- a/R/tiltTransitionRisk-package.R
+++ b/R/tiltTransitionRisk-package.R
@@ -15,6 +15,7 @@
 #' @importFrom rlang abort
 #' @importFrom stats quantile
 #' @importFrom tibble tribble
+#' @importFrom tiltIndicator categorize_risk
 #' @importFrom tiltIndicator epa_compute_profile_ranking
 #' @importFrom tiltIndicator spa_compute_profile_ranking
 #' @importFrom tiltToyData toy_emissions_profile_products_ecoinvent
diff --git a/man/add_transition_risk_category.Rd b/man/add_transition_risk_category.Rd
new file mode 100644
index 0000000..3acc236
--- /dev/null
+++ b/man/add_transition_risk_category.Rd
@@ -0,0 +1,37 @@
+% Generated by roxygen2: do not edit by hand
+% Please edit documentation in R/add_transition_risk_category.R
+\name{add_transition_risk_category}
+\alias{add_transition_risk_category}
+\title{Adds transition risk categories for transition risk scores}
+\usage{
+add_transition_risk_category(data)
+}
+\arguments{
+\item{data}{A dataframe}
+}
+\value{
+A dataframe.
+}
+\description{
+Adds transition risk categories for transition risk scores
+}
+\examples{
+library(tiltToyData)
+library(readr)
+library(dplyr)
+options(readr.show_col_types = FALSE)
+
+emissions_profile_products <- read_csv(toy_emissions_profile_products_ecoinvent())
+all_uuids_scenario_sectors <- read_csv(toy_all_uuids_scenario_sectors())
+scenarios <- read_csv(toy_sector_profile_any_scenarios())
+
+transition_risk_thresholds <- add_thresholds_transition_risk(
+  emissions_profile_products,
+  all_uuids_scenario_sectors,
+  scenarios
+)
+
+output <- add_transition_risk_category(transition_risk_thresholds)
+output
+}
+\keyword{internal}
diff --git a/tests/testthat/test-add_transition_risk_category.R b/tests/testthat/test-add_transition_risk_category.R
new file mode 100644
index 0000000..7f24a36
--- /dev/null
+++ b/tests/testthat/test-add_transition_risk_category.R
@@ -0,0 +1,23 @@
+test_that("if input data lacks crucial columns, errors gracefully", {
+  emissions_profile_products <- read_csv(toy_emissions_profile_products_ecoinvent())
+  all_uuids_scenario_sectors <- read_csv(toy_all_uuids_scenario_sectors())
+  scenarios <- read_csv(toy_sector_profile_any_scenarios())
+
+  input_data <- add_thresholds_transition_risk(
+    emissions_profile_products,
+    all_uuids_scenario_sectors,
+    scenarios
+  )
+
+  crucial <- col_transition_risk_score()
+  bad <- select(input_data, -all_of(crucial))
+  expect_error(add_transition_risk_category(bad), crucial)
+
+  crucial <- col_tr_low_threshold()
+  bad <- select(input_data, -all_of(crucial))
+  expect_error(add_transition_risk_category(bad), crucial)
+
+  crucial <- col_tr_high_threshold()
+  bad <- select(input_data, -all_of(crucial))
+  expect_error(add_transition_risk_category(bad), crucial)
+})