Understanding human activity in real-world situations often involves complicated data collection, analysis, and presentation methods. This article discusses how Cultural-Historical Activity Theory (CHAT) can inform design-based research practices that focus on understanding activity in real-world situations. I provide a sample data set with activity systems analyses of a yearlong teacher professional development program designed to foster technology integration into rural Indiana schools. I present the analytical dilemmas I faced while maintaining trustworthiness in the qualitative data analysis. Through the sample data analysis, I demonstrate how the school-wide technology reform initiative affected and was affected by classroom-based teacher technology implementation projects. Additionally, I introduce the theoretical findings from the data analyses that contribute to further development in activity systems analysis. (Contains 1 table, 1 footnote and 9 figures.) [Additional funding for this article was supported by the Ackerman Family Foundation. A version of this article was presented at the 2002 biannual meeting of the International Conference of the Learning Sciences.]