This article explores the overlap of symptoms between autism and attachment difficulties in adulthood. Clinicians express difficulties in differentiating between these conditions contributing to misdiagnosis. Distinguishing autism spectrum behaviors from behaviors relating to disorganized attachment can be challenging. Urgency is added by the fact that the number of cases is increasing in the diagnosis of autism spectrum disorder (ASD). It is becoming increasingly recognized that ASD shares phenotypic similarities with other traditionally distinct developmental conditions. This article aims enhance the clinicians' critical reasoning regarding the patient's behavior to distinguish if its autism or attachment-related behavior disorders. For us, the clearest differentiation factor seemed to be the nature of the behavior.