In two studies on mobile phone purchase decisions, we investigated consumers' decision strategies with a newly developed process tracing tool called InterActive Process Tracing (IAPT). This tool is a combination of several process tracing techniques (Active Information Search, Mouselab, and retrospective verbal protocol). After repeatedly choosing one of four mobile phones, participants formalized their strategy so that it could be used to make choices for them. The choices made by the identified strategies correctly predicted the observed choices in 73% (Experiment 1) and 67% (Experiment 2) of the cases. Moreover, in Experiment 2 we directly compared Mouselab and eye tracking with respect to their impact on information search and strategy description. We found only minor differences between these two methods. We conclude that IAPT is a useful research tool to identify choice strategies, and that using eye tracking technology did not increase its validity beyond that gained with Mouselab.