Advances in portable electronic technologies have created opportunities for the realtime assessment of children’s physical activity and eating behaviors in naturalistic situations. Mobile phones or PDA’s can be used to record electronic surveys, take photographs, or indicate geographic locations of children’s behaviors. Unlike self-report instruments, which are prone to recall errors and biases, real-time data capture (RTDC) methods can assess behaviors as they occur. In addition, these strategies are able to provide contextual information about physical activity and healthy eating such as where and with whom the behaviors are taking place; and how children feel before, during, and after these activities. This commentary will describe how RTDC methods can enhance our understanding of factors influencing children’s physical activity and eating behaviors. In particular, it will discuss the potential to advance research pertaining to the following questions: (1) How frequently, when, what amount, what intensity, what duration, and what type of food or activity was eaten or performed? (2) Where and with whom do children engage in physical activity and eat, and do these patterns differ according to demographic (e.g., sex, age, ethnic, income) and temporal (e.g., time of day, day of the week, seasonal) characteristics?; (3) How do children’s physical activity levels (e.g., intensity, duration) and eating patterns (e.g., amount/content of food) differ across physical and/or social contexts?; (4) To what extent do mood, stress, and psychosocial factors serve as time-related antecedents and consequences to children’s physical activity and eating episodes?; and (5) Are patterns of within-daily variability in children’s physical activity and eating behaviors related to health outcomes such as body weight, insulin dependence, and the metabolic syndrome? The commentary will also discuss practical and economic challenges associated with employing RTDC methodologies in research studies with children. It will conclude by addressing how these innovative research strategies can inform the design of programs and policies to prevent and treat childhood obesity.