Two experiments are reported that employed think-aloud methods to test predictions concerning relevance effects and rationalization processes derivable from Evans’ (1996) heuristic-analytic theory of the selection task. Evans’ account proposes that card selections are triggered by rele vance-determining heuristics, with analytic processing serving merely to rationalize heuristically-cued decisions. As such, selected cards should be associated with more references to both their facing and their hidden sides than rejected cards, which are not subjected to analytic rationalization. Experiment 1 used a standard selection-task paradigm, with negative components permuted through abstract conditional rules. Support was found for all heuristic-analytic predictions. This evidence was shown to be robust in Experiment 2, where “select-don’t select” decisions were enforced for all cards. Both experiments also clarify the role played by secondary heuristics in cueing the consideration of hidden card values during rationalization. We suggest that whilst Evans’ heuristic-analytic model and Oaksford and Chater’s (e.g., 2003) optimal data selection model can provide compelling accounts of our protocol findings, the mental models theory fares less well as an explanation of our full dataset.