Both nonaffective and affective psychoses are associated with deficits in social functioning across the course of the illness. However, it is not clear how social functioning varies among diagnostic groups as a function of age. The current study examined the relationship between social functioning and age in schizophrenia (SZ), schizoaffective disorder (SZA), and psychotic bipolar disorder (PBD). We found that individuals with PBD had the highest functioning, whereas individuals with SZ had the poorest. The functioning of individuals with SZA fell in between those of other groups. We also found that older ages were associated with poorer functioning. Although there was not a significant diagnostic group by age interaction, visual inspection of our data suggests a subtly steeper trajectory of decline in PBD. Overall, these results indicate that early interventions targeting social functioning may benefit individuals with either non-affective or affective psychoses to slow a projected decline.