To lock a study

1. Navigate to Tasks > Build Study
2. Next to "Set Study Status" select "Locked"
3. Click "Save Status"

To lock a site

1. Navigate to Tasks > Build Study
2. Next to Task 6 Create Sites, click the View icon.
3. Find the Site you want to lock. Select the Edit icon.
4. Scroll down towards the bottom and find "Site Status for this study." Select "locked."
5. Click "Submit Site"

To lock an event for a subject

1. Navigate to the Subject Matrix.
2. Find the Subject & Event you want to lock.
3. Click "View/Enter Data" for the Event you want to lock.
4. At the top, click "Edit Study Event"
5. Next to status, select "locked."
6. Click "Submit changes"

The above describes the "normal" situation where you lock an event for a subject once the event has been marked complete (i.e. all forms are either marked complete or not started). But you can also lock an empty event to prevent data entry:

1. Schedule the event
2. Open one of the event CRFs for initial data entry but do not save anything and close the CRF
3. Change event status to stopped
4. Change event status to locked