diff --git a/extensions/measurement-tracking/src/contexts/TrackedMeasurementsContext/index.js b/extensions/measurement-tracking/src/contexts/TrackedMeasurementsContext/index.js
new file mode 100644
index 000000000..84aafd9bd
--- /dev/null
+++ b/extensions/measurement-tracking/src/contexts/TrackedMeasurementsContext/index.js
@@ -0,0 +1,70 @@
+import React, { useContext, useReducer } from 'react';
+
+const TRACKED_MEASUREMENTS_INITIAL_STATE = {
+  /** StudyInstanceUID */
+  trackedStudy: '',
+  /** string[] of SeriesInstanceUID */
+  trackedSeries: [],
+  /** key, value => displaySetInstanceUID, string label */
+  viewportLabels: new Map(),
+};
+
+const TrackedMeasurementsContext = React.createContext();
+
+TrackedMeasurementsContext.displayName = 'TrackedMeasurementsContext';
+
+const useTrackedMeasurements = () => useContext(TrackedMeasurementsContext);
+
+/**
+ *
+ * @param {*} param0
+ */
+function TrackedMeasurementsContextProvider({ children }) {
+  /**
+   *
+   * @param {object} state - previous state
+   * @param {object} action
+   * @param {string} action.type
+   * @param {object} action.payload
+   */
+  const reducer = (state, action) => {
+    switch (action.type) {
+      case 'TRACK_SERIES':
+        const { StudyInstanceUID, SeriesInstanceUID } = action.payload;
+        return state;
+      case 'UNTRACK_SERIES':
+        return state;
+      default:
+        return state;
+    }
+  };
+
+  // Computed:
+  // numTrackedSeries
+
+  // API
+  // -
+  // - TrackSeries(studyUid, seriesUid) (or... TrackViewport?)
+  //    - Checks against tracked study + series
+  //    - Initiates prompt if required
+  //    - does nothing for SR modality? (how do we know SR viewport?????????)
+  // - UntrackSeries(seriesUid)
+  const [trackedMeasurements, dispatchTrackedMeasurements] = useReducer(
+    reducer,
+    TRACKED_MEASUREMENTS_INITIAL_STATE
+  );
+
+  return (
+    <TrackedMeasurementsContext.Provider
+      value={[trackedMeasurements, dispatchTrackedMeasurements]}
+    >
+      {children}
+    </TrackedMeasurementsContext.Provider>
+  );
+}
+
+export {
+  TrackedMeasurementsContext,
+  TrackedMeasurementsContextProvider,
+  useTrackedMeasurements,
+};
diff --git a/extensions/measurement-tracking/src/contexts/TrackedMeasurementsContext/trackedMeasurementsStateMachine.js b/extensions/measurement-tracking/src/contexts/TrackedMeasurementsContext/trackedMeasurementsStateMachine.js
new file mode 100644
index 000000000..e19044b41
--- /dev/null
+++ b/extensions/measurement-tracking/src/contexts/TrackedMeasurementsContext/trackedMeasurementsStateMachine.js
@@ -0,0 +1,116 @@
+import { Machine, interpret } from 'xstate';
+
+// {
+//   "type": "TRACK_SERIES",
+//   "StudyInstanceUID": "study1",
+//   "SeriesInstanceUID": "series1"
+// }
+
+// TODO:
+// userPrompts should invoke promises:
+// https://egghead.io/lessons/xstate-invoking-a-promise-for-asynchronous-state-transitions-in-xstate
+
+const config = {
+  id: 'measurementTracking',
+  initial: 'notTracking',
+  context: {
+    prevTrackedStudy: '',
+    prevTrackedSeries: [],
+    trackedStudy: '',
+    trackedSeries: [],
+  },
+  states: {
+    notTracking: {
+      on: {
+        TRACK_SERIES: {
+          target: 'userPromptShouldTrack',
+          actions: 'trackSeries',
+        },
+      }
+    },
+    userPromptShouldTrack: {
+      on: {
+        YES: 'tracking',
+        CANCEL: 'notTracking',
+        NEVER: 'neverTracking',
+      },
+    },
+    neverTracking: {
+      type: 'final',
+    },
+    tracking: {
+      on: {
+        TRACK_SERIES: [
+          { target: 'tracking', cond: 'hasNewSeriesForTrackedStudy', actions: 'trackSeries' },
+          { target: 'userPromptTrackingConflict', cond: 'hasConflictingStudyInstanceUID', actions: ['setPrevTracked', 'clearTrackedSeries', 'trackSeries'] },
+        ],
+        UNTRACK_SERIES: [
+          { target: 'tracking', cond: '', actions: ''},
+          { target: 'notTracking', cond: '', actions: '' },
+        ],
+      },
+    },
+    userPromptShouldTrackNewStudy: {
+      on: {
+        CANCEL: {
+          target: 'tracking',
+          actions: 'restorePrevTracked',
+        },
+        YES: 'tracking',
+      },
+    },
+  },
+  strict: true,
+};
+
+// Actions:
+// - entry
+// - exit
+// - transition (on)
+
+// Activities:
+// - can return a "clean-up" function to call on exit
+
+// actions, guards, services, activities, delays
+const options = {
+  actions: {
+    logStuff: (context, event) => { console.log(context, event ) },
+    setPrevTracked: assign(context => ({
+      prevTrackedStudy: context.trackedStudy,
+      prevTrackedSeries: context.trackedSeries.slice(),
+    })),
+    restorePrevTracked: assign(context => ({
+      trackedStudy: context.prevTrackedStudy,
+      trackedSeries: context.prevTrackedSeries.slice(),
+    })),
+    clearTrackedSeries: assign(() => ({
+      trackedStudy: '',
+      trackedSeries: [],
+    })),
+    trackSeries: assign((context, event) =>
+      {
+        console.log(context, event);
+        const prevTrackedSeries = context.trackedSeries.slice();
+        return {
+          trackedStudy: event.StudyInstanceUID || '',
+          trackedSeries: [...prevTrackedSeries, event.SeriesInstanceUID],
+        }
+    }),
+  },
+  guards: {
+    hasConflictingStudyInstanceUID: (context, event) =>
+      context.StudyInstanceUID !== context.trackedStudy,
+    hasNewSeriesForTrackedStudy: (context, event) =>
+      event.StudyInstanceUID === context.trackedStudy &&
+      !context.trackedSeries.includes(event.SeriesInstanceUID),
+  },
+}
+
+const measurementTrackingMachine = Machine(config, options);
+// .transition(state, eventArgument).value
+const service = interpret(measurementTrackingMachine).start();
+// .send(event): nextState
+// .state (getter)
+// .onTransition(state => { state.vale })
+
+export default measurementTrackingMachine;
diff --git a/extensions/measurement-tracking/src/contexts/index.js b/extensions/measurement-tracking/src/contexts/index.js
new file mode 100644
index 000000000..8b6723a0e
--- /dev/null
+++ b/extensions/measurement-tracking/src/contexts/index.js
@@ -0,0 +1,5 @@
+export {
+  TrackedMeasurementsContext,
+  TrackedMeasurementsContextProvider,
+  useTrackedMeasurements,
+} from './TrackedMeasurementsContext';