The PFC plays a crucial role in coordinating sensory, motor and cognitive processes for goal-directed behavior. The response properties of its neurons have been extensively studied, with findings generally pointing to functional heterogeneity and complex, mixed selectivity. How these properties are computed by the PFC microcircuit, however, is much less understood. To study this, we used a combination of behavior, pharamacology and microendoscopic calcium imaging from genetically identified cell types in the mouse dorsomedial PFC. First, we showed that this region is required for performance of a sensory discrimination task. Moreover, we found that inhibitory interneurons of the same subtype were similar to each other, but different subtypes preferentially signaled different task-related events: somatostatin-positive neurons primarily signaled motor action, vasoactive intestinal peptide-positive neurons responded strongly to action outcomes, whereas parvalbumin-positive neurons were less selective, responding to sensory cues, motor action, and trial outcomes. Compared to each interneuron subtype, pyramidal neurons showed much greater functional heterogeneity, and their responses varied across cortical layers. Such cell-type and laminar differences in neuronal functional properties may be crucial for local computation within the PFC microcircuit, and provide important contraints for future computational models of PFC function.