This tutorial will offer an overview of systematic observation as a primary tactic for assessing physical activity (PA) in physical education classes, school campuses, and park/recreation settings. Direct observation is a widely used data collection tactic for this purpose. PA behavior always occurs in social contexts/environments. Therefore, specific emphasis will be placed on the importance of collecting data on contextual variables. Attendees will learn about the mechanics of systematic observation, advantages of direct observation over other measurement tools (e.g., HR monitors, accelerometry, etc.), resulting data output, limits of direct observation, and validation issues of observation systems for PA.