Clinical reasoning is a complex process whereby psychologists review a large amount of data to generate diagnostic conclusions. Limited research has studied clinical reasoning specific to psychoeducational assessment. In this study, we used a think-aloud protocol to examine trainees' and licensed practitioners' clinical reasoning as they completed an unfolding case. Data were collected on efficiency (time spent on case, amount and order of diagnostic information requested), accuracy, and confidence, with the expectation that these areas would be more developed in experienced practitioners. Analyses found no effect of experience on clinical reasoning efficiency. However, trainees were less confident and accurate in their diagnostic conclusions and more likely to be influenced by contextual information that was less core to the diagnosis. These findings suggest that previous exposure to specific disorders is beneficial to clinical reasoning development and suggests a need for systemic training related to a broad range of disorders in graduate programs.