The present paper provides a task analysis for creating a computerized data system using a Pocket PC and Microsoft Visual Basic. With Visual Basic software and any handheld device running the Windows MOBLE operating system, this task analysis will allow behavior analysts to program and customize their own functional analysis data-collection system. The program will allow the user to select the type of behavior to be recorded, choose between interval and frequency data collection, and summarize data for graphing and analysis. We also provide suggestions for customizing the data-collection system for idiosyncratic research and clinical needs. (Contains 2 tables, and 4 figures.)