["Autism Research, Volume 19, Issue 4, April 2026. ", "\nABSTRACT\nBoth autism spectrum disorder (ASD) and psychosis are associated with challenges in social cognition. The triple‐network model posits that dysfunction within and between the default mode network (DMN), central executive network (CEN), and salience network (SN) contributes to these deficits. However, the relationship between triple‐network connectivity and social cognition has not been systematically compared across these groups during adolescence. We examined whole‐brain functional connectivity of the triple‐network in a sample of youth with ASD (N = 24), youth with early‐onset psychosis (EOP; N = 25), and age‐matched typically developing (TD) controls (N = 26, overall mean age = 16.39 ± 2.36, % female = 41%). Additionally, we examined relationships between connectivity patterns of the triple‐network and behavioral measures of social cognition and emotion recognition in each group. ASD youth showed mixed over‐ and under‐connectivity in the DMN, CEN overconnectivity, and SN underconnectivity, while EOP youth showed DMN and CEN overconnectivity, with relatively intact SN connectivity, compared to TD controls. Compared to EOP, ASD participants had reduced SN connectivity and mixed disruptions in DMN connectivity. Across groups, connectivity patterns were linked to social behaviors: in EOP, DMN overconnectivity was associated with poorer social cognition; in ASD, SN underconnectivity was associated with poorer social cognition. These findings highlight both shared and distinct patterns of triple‐network dysconnectivity in ASD and EOP, supporting transdiagnostic models of social cognitive dysfunction, and reinforcing adolescence as a key developmental window for network‐based brain changes.\n"]