Depression symptoms that onset during early childhood are increasingly recognized as a significant public health concern. A proliferation of research over the last 2 decades has identified preschool depression as a diagnostic reality that is associated with a severe and persistent course of depression throughout the lifespan. The current review summarizes the research on preschool depression from the last 7 years (2017–2024), with a particular focus on the assessment of, factors and outcomes associated with, neurobiological underpinnings of, and treatments for preschool depression. We also discuss potential avenues of inquiry that further elucidate the nature of preschool depression.