diff --git a/.github/workflows/unit_tests.yml b/.github/workflows/unit_tests.yml
new file mode 100644
index 00000000..35aaa0af
--- /dev/null
+++ b/.github/workflows/unit_tests.yml
@@ -0,0 +1,42 @@
+# This is a basic workflow to help you get started with Actions
+
+name: Build and run unit tests
+
+# Controls when the workflow will run
+on:
+  # Triggers the workflow on push or pull request events but only for the "main" branch
+  push:
+    branches: [ "main", "testing" ]
+  pull_request:
+    branches: [ "main", "testing" ]
+
+  # Allows you to run this workflow manually from the Actions tab
+  workflow_dispatch:
+
+# A workflow run is made up of one or more jobs that can run sequentially or in parallel
+jobs:
+  # This workflow contains a single job called "build"
+  build:
+    # The type of runner that the job will run on
+    runs-on: ubuntu-latest
+        
+    # Steps represent a sequence of tasks that will be executed as part of the job
+    steps:
+      # Checks-out your repository under $GITHUB_WORKSPACE, so your job can access it
+      - uses: actions/checkout@v3
+        with:
+          submodules: 'recursive'
+
+      - run: sudo apt-get update -qq
+      - run: sudo add-apt-repository -y ppa:ubuntu-toolchain-r/test
+      - run: sudo apt-get update -qq
+      - run: sudo apt-get install -qq cmake build-essential python3-pip python3-virtualenv nodejs tar gzip libpthread-stubs0-dev libc6-dbg gdb
+      - run: g++ --version
+      - name: Build tests
+        run: |
+          cmake ..
+          cmake --build .
+        working-directory: tests/build
+      - name: Run tests
+        run: ./run_tests.sh
+        working-directory: tests/build
diff --git a/.gitmodules b/.gitmodules
new file mode 100644
index 00000000..61932e24
--- /dev/null
+++ b/.gitmodules
@@ -0,0 +1,3 @@
+[submodule "third_party/Catch2"]
+	path = third_party/Catch2
+	url = https://github.com/catchorg/Catch2.git
diff --git a/docs/HowToTest.md b/docs/HowToTest.md
new file mode 100644
index 00000000..e80c0a55
--- /dev/null
+++ b/docs/HowToTest.md
@@ -0,0 +1,99 @@
+This guide will demonstrate how to create, build, and run tests.
+
+***Note:*** that these instructions should work on Mac and Linux systems. Windows instructions should be similar, but please add any information about working with tests on Windows via a pull request! 
+
+***Note:*** this guide assumes you have Catch2 downloaded. 
+If you haven't yet downloaded the repo, simply add a `--recursive` to the end of your `git clone`. 
+If you _have_ downloaded the rest of the repo, simply initialize and update the submodules: 
+```
+git submodule init
+git submodule update
+```
+
+## How to compile tests
+
+First, navigate to the `tests` directory. 
+```
+cd tests
+```
+
+Create a build directory within `tests`, if it does not already exist.
+```
+mkdir build
+```
+Note that this will likely through an error/warning if the directory already exists. 
+
+Navigate into the `build` directory. 
+```
+cd build
+```
+
+Now we need to use CMake to compile. This is a two step process.
+First we tell CMake where to find the files, relative to our current directory. 
+```
+cmake ..
+```
+
+If that completes without errors, we can now build the files in our current directory. 
+```
+cmake --build .
+```
+
+That should compile the unit tests. 
+Note that this process will take a while the first time as it needs to compile Catch2. It should be much faster in subsequent builds. 
+
+## Running tests
+
+If you are on a Mac or Linux system and wish to run _all_ the unit tests, simply run 
+```
+./run_tests.sh
+```
+from _within the `build` directory_ (not just in `tests`). 
+
+If you wish to run a particular test (or are on Windows), simply navigate to the test _within the build directory_. 
+For example, if we want to run tests for `WorldGrid` (which is in core), we would navigate like so: 
+```
+cd unit/core
+```
+
+Once we're in the correct directory, we simply run the executable. 
+On Unix systems that looks like: 
+```
+./tests-unit-core-WorldGrid
+```
+On Windows it should be similar, though it may have a `.exe` extension.
+
+## Adding new tests
+
+To add tests for a new file, navigate to the corresponding folder in the `tests/unit` directory (not in `tests/build`. 
+For example, if we want to add a test for a new file in `core`, from the root of the repo we would navigate like so: 
+```
+cd tests/unit/core
+```
+Once in the correct directory we need to add the actual source code of the test. 
+This should be done as a new `.cpp` file, which will typically have the same name as the header file in source (_e.g._, `WorldGrid.hpp` will have a new test file called `WorldGrid.cpp`). 
+
+Once you've created that file, you can start with this skeleton code: 
+
+```
+/**
+ * This file is part of the Fall 2023, CSE 491 course project.
+ * @brief <TODO>
+ **/
+
+// Catch2 
+#define CATCH_CONFIG_MAIN
+#include <catch2/catch_all.hpp>
+
+// Class project
+// Place your includes here
+// e.g., #include "core/Data.hpp"
+  
+TEST_CASE("NAME", "[tags]"){
+}
+
+```
+
+Finally, once you have some tests coded up, you need to make one more change. 
+Simply add the name of that file (including the `.cpp`!) to `targets.txt`. 
+CMake uses this file to ensure we compile the appropriate files. 
diff --git a/docs/README.md b/docs/README.md
index 5386d5d3..7c447ff0 100644
--- a/docs/README.md
+++ b/docs/README.md
@@ -9,3 +9,5 @@ Below are a set of guides for how to develop your own modules and joining them t
 - [How to Build an Interface](HowToBuildAnInterface.md) - How to build an interface that allows a human user to control an agent.
 
 - [How to Assemble a `main()` function](HowToAssembleAMain.md) - A guide to selecting worlds, agents, and interfaces and turning them into a custom executable (including how to collect data about the resulting system.)
+
+- [How to build, run, and create unit tests](HowToTest.md) - Walks through how to build and run existing unit tests, as well as create new unit test files. 
diff --git a/source/core/WorldGrid.hpp b/source/core/WorldGrid.hpp
index a3405a34..bc8de740 100644
--- a/source/core/WorldGrid.hpp
+++ b/source/core/WorldGrid.hpp
@@ -15,6 +15,7 @@
 
 #include "CoreObject.hpp"
 #include "GridPosition.hpp"
+#include "Data.hpp"
 
 namespace cse491 {
 
@@ -194,4 +195,4 @@ namespace cse491 {
 
   };
 
-} // End of namespace cse491
\ No newline at end of file
+} // End of namespace cse491
diff --git a/tests/.gitignore b/tests/.gitignore
new file mode 100644
index 00000000..c09e3d48
--- /dev/null
+++ b/tests/.gitignore
@@ -0,0 +1,6 @@
+# Vim swap files
+*.swp
+*.swo
+
+# CMake files and directories
+CMakeFiles
diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
new file mode 100644
index 00000000..72b0b6f5
--- /dev/null
+++ b/tests/CMakeLists.txt
@@ -0,0 +1,17 @@
+cmake_minimum_required(VERSION 3.10) 
+project(tests VERSION 0.1)
+
+set(CMAKE_CXX_STANDARD 20)
+set(CMAKE_CXX_STANDARD_REQUIRED True)
+
+set(CATCH_SRC_DIR ../third_party/Catch2)
+set(CATCH_BUILD_DIR catch_build)
+set(MAIN_SOURCE_DIR ../source)
+
+configure_file(run_tests.sh run_tests.sh COPYONLY)
+
+# Catch2 CMake integration
+# From https://github.com/catchorg/Catch2/blob/devel/docs/cmake-integration.md#top
+add_subdirectory(${CATCH_SRC_DIR} ${CATCH_BUILD_DIR})
+
+add_subdirectory(unit)
diff --git a/tests/build/.gitignore b/tests/build/.gitignore
new file mode 100644
index 00000000..72e8ffc0
--- /dev/null
+++ b/tests/build/.gitignore
@@ -0,0 +1 @@
+*
diff --git a/tests/run_tests.sh b/tests/run_tests.sh
new file mode 100755
index 00000000..a2d51a9a
--- /dev/null
+++ b/tests/run_tests.sh
@@ -0,0 +1,27 @@
+#!/bin/bash
+
+run_tests () {
+  local DIR_NAME=$(pwd | grep -oP "/\w+$" | grep -oP "\w+")
+  local FILENAMES=$(ls tests-unit-* 2> /dev/null)
+  for FILENAME in ${FILENAMES}
+  do
+    echo "Running test: ${FILENAME}"
+    ./${FILENAME}
+  done
+}
+
+cd unit
+TARGETS="core Agents Worlds Interfaces"
+for TARGET in ${TARGETS}
+do
+if [ -d ${TARGET} ]
+  then
+    echo "Entering ${TARGET}"
+    cd ${TARGET}
+    run_tests
+    echo "Exiting ${TARGET}"
+  else
+    echo "Directory not found: ${TARGET}. Skipping."
+  fi
+done
+cd ..
diff --git a/tests/unit/CMakeLists.txt b/tests/unit/CMakeLists.txt
new file mode 100644
index 00000000..cb96d01a
--- /dev/null
+++ b/tests/unit/CMakeLists.txt
@@ -0,0 +1,5 @@
+cmake_minimum_required(VERSION 3.10) 
+
+
+set(MAIN_SOURCE_DIR ../${MAIN_SOURCE_DIR})
+add_subdirectory(core)
diff --git a/tests/unit/core/CMakeLists.txt b/tests/unit/core/CMakeLists.txt
new file mode 100644
index 00000000..15af4f55
--- /dev/null
+++ b/tests/unit/core/CMakeLists.txt
@@ -0,0 +1,20 @@
+cmake_minimum_required(VERSION 3.10) 
+#project(tests-unit VERSION 0.1)
+
+set(CMAKE_CXX_STANDARD 20)
+set(CMAKE_CXX_STANDARD_REQUIRED True)
+
+file(STRINGS targets.txt TARGETS)
+
+set(MAIN_SOURCE_DIR ../${MAIN_SOURCE_DIR})
+
+foreach(TARGET IN LISTS TARGETS)
+  add_executable(tests-unit-core-${TARGET} ${TARGET}.cpp)
+
+  target_include_directories(tests-unit-core-${TARGET}
+    PRIVATE ${MAIN_SOURCE_DIR}
+    )
+  target_link_libraries(tests-unit-core-${TARGET}
+    PRIVATE Catch2::Catch2WithMain
+    )
+endforeach()
diff --git a/tests/unit/core/Data.cpp b/tests/unit/core/Data.cpp
new file mode 100644
index 00000000..48fcf188
--- /dev/null
+++ b/tests/unit/core/Data.cpp
@@ -0,0 +1,20 @@
+/**
+ * This file is part of the Fall 2023, CSE 491 course project.
+ * @brief Unit tests for Data.hpp in source/core
+ **/
+
+// Catch2 
+#define CATCH_CONFIG_MAIN
+#include <catch2/catch_all.hpp>
+
+// Class project
+#include "core/Data.hpp"
+#include "core/Entity.hpp"
+#include "core/AgentBase.hpp"
+
+TEST_CASE("CellType", "[core]"){
+  cse491::CellType cell_type("name", "desc", '@');
+  CHECK(cell_type.name == "name");
+  CHECK(cell_type.desc == "desc");
+  CHECK(cell_type.symbol == '@');
+}
diff --git a/tests/unit/core/WorldGrid.cpp b/tests/unit/core/WorldGrid.cpp
new file mode 100644
index 00000000..b8bc6597
--- /dev/null
+++ b/tests/unit/core/WorldGrid.cpp
@@ -0,0 +1,49 @@
+/**
+ * This file is part of the Fall 2023, CSE 491 course project.
+ * @brief Unit tests for Data.hpp in source/core
+ **/
+
+// Catch2 
+#define CATCH_CONFIG_MAIN
+#include <catch2/catch_all.hpp>
+
+// Class project
+#include "core/WorldGrid.hpp"
+
+TEST_CASE("WorldGrid Construction", "[core][grid]"){
+  SECTION("Default construction"){
+    cse491::WorldGrid grid;
+    CHECK(grid.GetWidth() == 0);
+    CHECK(grid.GetWidth() == 0);
+    CHECK(grid.GetNumCells() == 0);
+    CHECK(!grid.IsValid(0, 0));
+    CHECK(!grid.IsValid(1, 1));
+    CHECK(!grid.IsValid(-1, -1));
+  }
+  SECTION("Standard construction, no type"){
+    cse491::WorldGrid grid(10, 10);
+    CHECK(grid.GetWidth() == 10);
+    CHECK(grid.GetWidth() == 10);
+    CHECK(grid.GetNumCells() == 100);
+    CHECK(grid.IsValid(0, 0));
+    CHECK(grid.IsValid(1, 1));
+    CHECK(grid.IsValid(9, 9));
+    CHECK(!grid.IsValid(0, 10));
+    CHECK(!grid.IsValid(10, 0));
+    CHECK(!grid.IsValid(-1, -1));
+  }
+}
+// TODO: Test resizing to a smaller size
+// TODO: Check that resizing keeps the cells that are not lost / new
+TEST_CASE("WorldGrid Resize", "[core][grid]"){
+  SECTION("Resize to larger"){
+    cse491::WorldGrid grid;
+    CHECK(grid.GetWidth() == 0);
+    CHECK(grid.GetWidth() == 0);
+    CHECK(grid.GetNumCells() == 0);
+    grid.Resize(10, 10);
+    CHECK(grid.GetWidth() == 10);
+    CHECK(grid.GetWidth() == 10);
+    CHECK(grid.GetNumCells() == 100);
+  }
+}
diff --git a/tests/unit/core/targets.txt b/tests/unit/core/targets.txt
new file mode 100644
index 00000000..773d3a00
--- /dev/null
+++ b/tests/unit/core/targets.txt
@@ -0,0 +1,2 @@
+Data
+WorldGrid
diff --git a/third_party/Catch2 b/third_party/Catch2
new file mode 160000
index 00000000..9c541ca7
--- /dev/null
+++ b/third_party/Catch2
@@ -0,0 +1 @@
+Subproject commit 9c541ca72e7857dec71d8a41b97e42c2f1c92602