Pediatric trigger thumb and congenital clasped thumb are the two most common pediatric thumb flexion deformities. Both might appear similar, however, they are caused by varying etiologies, and treatment is vastly different. Pediatric trigger thumb is due to a size mismatch of the flexor tendon and the thumb pulley system, develops over time, typically manifests as a locked interphalangeal joint, and is treated with observation or surgical release. Congenital clasped thumb, although presenting in varying degrees of severity, is due to a congenital absence or hypoplasia of one or more of the thumb extensors and is treated with either splinting for supple deformities or surgery for more complex deformities.