Imagistic reasoning appears to be a critical strategy for learning and problem solving in the sciences, particularly chemistry; however, little is known about how students use imagistic reasoning on genuine assessment tasks in chemistry. The present study employed a think-aloud protocol to explore when and how students use imagistic reasoning for problem solving in organic chemistry. The analysis suggests that students employ imagistic reasoning preferentially for translating between various molecular representations. On more complex tasks typical of classroom assessments, the students' problem solving appears mostly dependent on the accuracy of self-generated inscriptions rather than the use of imagistic reasoning. The results indicate a variable interplay between imagistic reasoning and diagrammatic reasoning that suggests several pedagogical implications for teaching college chemistry. (Contains 3 tables and 6 figures.)