diff --git a/.gitignore b/.gitignore
index 7fa4848e..f627022a 100644
--- a/.gitignore
+++ b/.gitignore
@@ -11,6 +11,7 @@
 *.rd[as]
 
 # Python
+.tox
 .coverage
 coverage
 cov.xml
diff --git a/Makefile b/Makefile
index c5dd6874..74668b94 100644
--- a/Makefile
+++ b/Makefile
@@ -30,6 +30,8 @@ PYPI_REPO ?= testpypi
 REPORTS_DIR ?= reports
 BANDIT_REPORT := bandit.sarif
 PYTEST_REPORT := pytest
+PYTEST_TARGET ?= .
+TOX_DIR := .tox
 
 
 # Can be overridden. This is used to change the prereqs
@@ -195,7 +197,7 @@ test-bandit : $(VENV) $(BUILD_TARGET)
 
 test-pytest : $(VENV) $(BUILD_TARGET)
 	-$(ACTIVATE_VENV) && \
-	pytest $(PYTEST_FLAGS) && PYTEST_EXIT_CODE=0 || PYTEST_EXIT_CODE=$$?; \
+	PYTEST_TARGET=$(PYTEST_TARGET) tox && PYTEST_EXIT_CODE=0 || PYTEST_EXIT_CODE=$$?; \
 	coverage html --data-file=$(REPORTS_DIR)/$(PYTEST_REPORT)/.coverage; \
 	junit2html $(REPORTS_DIR)/$(PYTEST_REPORT)/pytest.xml $(REPORTS_DIR)/$(PYTEST_REPORT)/pytest.html; \
 	exit $$PYTEST_EXIT_CODE
@@ -230,6 +232,7 @@ clean-build :
 
 clean-test :
 	$(CMD_PREFIX)rm -rf \
+		$(TOX_DIR) \
 		$(REPORTS_DIR)/$(PYTEST_REPORT) \
 		$(REPORTS_DIR)/$(BANDIT_REPORT)
 
diff --git a/pyproject.toml b/pyproject.toml
index d3e64d4c..788e8bf3 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -82,14 +82,13 @@ packages = [
 #
 [project.optional-dependencies]
 dev-dependencies = [
+    "tox ~= 4.18",
     "pytest ~= 8.0",
     "pytest-mock",
     "mock",
     "pytest-cov >= 4.1,< 5.0",
     "coverage ~= 7.4",
     "junit2html >= 30.1,< 32.0",
-    # Pyright >= 1.1.367 breaks the build.
-    # Waiting for new pyright release to fix it. https://github.com/uclahs-cds/BL_Python/issues/79
     "pyright == 1.1.379",
     "isort ~= 5.13",
     "ruff ~= 0.3",
@@ -183,7 +182,6 @@ addopts = [
     # https://github.com/microsoft/vscode-python/issues/21255
     # and
     # https://github.com/microsoft/vscode-python/issues/21845
-    "--cov=.",
     "--junitxml=reports/pytest/pytest.xml",
     "-o=junit_family=xunit2",
     "--cov-report=xml:reports/pytest/cov.xml",
@@ -194,6 +192,32 @@ python_files = "test_*.py"
 
 norecursedirs = "__pycache__ build .pytest_cache *.egg-info .venv .github-venv"
 
+[tool.tox]
+legacy_tox_ini = """
+    [tox]
+    envlist = py310
+
+    [testenv]
+    # these options make Tox use the existing .venv dir created by venv
+    envdir = .venv
+    usedevelop = true
+    recreate = false
+    skip_install = true
+
+    setenv =
+        # configure --cov here because we can't use
+        # envvars in pyproject.toml, and we want this
+        # to be configurable in order to test coverage
+        # for a subset of tests in the monorepo rather
+        # than for all tests in the repo.
+        PYTEST_ADDOPTS = --cov={env:PYTEST_TARGET:.}
+        # additional pytest flags - defaults to no flags
+        PYTEST_FLAGS = {env:PYTEST_FLAGS:}
+    commands =
+        # use `.` add the default --cov option if it's not specified
+        pytest {env:PYTEST_FLAGS} {env:PYTEST_ADDOPTS:--cov=.} {env:PYTEST_TARGET}
+"""
+
 [tool.coverage.report]
 include_namespace_packages = true