Physical activity is place-based, and being able to assess the number of people and their characteristics in specific locations is important both for public health surveillance and for practitioners in their design of physical activity spaces and programs. Although physical activity measurement has improved recently, many investigators avoid or are at a loss regarding the assessment of physical activity in explicit locations, especially in open environments where many people come and go in a seemingly indiscriminate fashion. Direct, systematic observation exceeds other methods in simultaneously assessing physical activity and the contexts in which it occurs. This commentary summarizes the development and use of 2 validated observation tools: the System for Observing Play and Leisure in Youth (SOPLAY) and System for Observing Play and Active Recreation in Communities (SOPARC). Their use is well supported by both behavior-analytic principles and social-ecological theory, and their methods have utility for both researchers and practitioners.