Childhood disintegrative disorder (CDD) is a rare pervasive developmental disorder that involves regression after a period of at least 2 years of typical development. This case study presents data from family home movies, coded by reliable raters using an objective coding system, to examine the trajectory of development in one child with a reported regression at 48 months of age. Coding substantiated parent reports of mostly typical early development, followed by later catastrophic loss of skills across many developmental domains. Differential diagnosis of CDD and autism with regression is discussed.