Most low earth orbit (LEO) satellites and some geostationary (GEO) satellites rely on GPS/GNSS for timing and positioning. This includes real-time onboard operations for scheduling ground contacts, executing mission functions, and tagging data records; as well as gathering observations for precise orbit determination. Highly stable clocks, like CSACs, are not required when using GNSS, but they can provide significant benefits in detecting invalid observations, coasting through periods of reduced GNSS visibility, and supporting navigation based on one-way ranging from ground transmitters. This tutorial will cover these applications and the expected performance of CSACs operating onboard small satellites. Dr. Penny Axelrad is Distinguished Professor in the Smead Aerospace Engineering Sciences Department, at the University of Colorado Boulder. Her research interests include technology and algorithms for PNT and remote sensing.