OBJECTIVE There is limited research on the effects of sociodemographic and socioeconomic factors on treatment outcomes in youth at clinical high risk for psychosis (CHRp). This study examined sociodemographic factors that may affect functional outcomes within this population. Specifically, we investigated the influence of race/ethnicity (dichotomized as non-Hispanic whites [NHW] vs. people of colour [POC]), socioeconomic status (SES; operationalized as parental years of education), and their interaction on change in psychosocial functioning and symptoms over 6 months in a randomized trial of family-focused therapy. METHODS CHRp youth (N = 128) participated in a randomized trial of family therapy (18 sessions of family therapy vs. 3 sessions of family psychoeducation). Sixty-four participants who self-identified as POC and 64 self-identified NHW participants completed baseline and 6-month follow-up measures of positive and negative symptoms and psychosocial (global, role, and social) functioning. Multiple regression models were conducted to test the main effect of race/ethnicity on changes in positive and negative symptoms and functioning, and whether this effect was moderated by parental education. RESULTS There was a significant interaction between race/ethnicity and parental education, such that higher parental education was associated with greater improvement in global functioning in NHW participants, but there was no relationship between parental education and global functioning in POC. Additionally, higher parental education was associated with a decrease in negative symptoms in NHW participants but not in POC. There were no significant effects of race/ethnicity or parental education on positive symptoms, nor on social or role functioning. CONCLUSIONS Clinicians may consider tailoring psychosocial treatments according to the needs of diverse families who vary in sociodemographic factors such as educational attainment and race/ethnicity.