TPACKtivity is discussed as a means to examine preservice teachers’ TPACK development. TPACKtivity employs activity theory to identify objectives, mediating tools, rules and community, as part of activity settings that contribute to, or detract from, TPACK development. The lens is described and applied in examining seven preservice teachers’ experiences and perceptions of various activity settings’ impacts on their learning to teach disciplinary content with technology. The TPACKtivity lens identified mediating tools for developing TPACK, made explicit the roles of the community members in contributing toward subjects’ TPACK development, and brought to light rules about technology use in classrooms that impact TPACK development. The findings illustrate the effectiveness of the TPACKtivity lens in sorting through the complexities of TPACK development across multiple settings.