PurposePsychosis and substance use disorders (SUDs) are highly prevalent and often co-occurring among homeless youth. EQIIP SOL, a specialized intensive outreach program within an early intervention service, provides 3-year comprehensive care for first-episode psychosis (FEP) homeless youth, targeting psychosis, SUD, and homelessness. This study aims to examine clinical and functional outcomes, along with predictors of housing stability, among youth enrolled in the program since its inception in 2012.MethodsThis longitudinal study examined the 3-year outcomes of all youth admitted to EQIIP SOL from 2012 to 2020. The inclusion criteria encompassed youth aged 18-30 years, diagnosed with primary psychosis and SUD and experiencing homelessness. Assessments were conducted at baseline and at 1, 3, 6, 9, 12, 15, 18, 24, and 36 months thereafter to describe housing stability, illness severity, and general functioning evolutions. Alcohol and substance use were evaluated at baseline and annually. A multivariate mixed-effects model investigated baseline predictors of housing stability.ResultsOf the 177 enrolled youth, 81.4% achieved housing stability at least once, within a median of six months. Improvements in illness severity and general functioning were observed during the initial nine months, plateauing thereafter. SUDs reduced approximately by one-third; alcohol use disorder decreased by half. Older age (OR = 1.18 (1.07-1.31)), no history of chronic homelessness (OR = 2.16 (1.13-4.13)), stimulant addiction (OR = 0.51 (0.26-0.98)) and being roofless/emergency sheltered at admission (OR = 0.41 (0.19-0.88)) were associated with housing stability.ConclusionEQIIP SOL's integrated approach yields promising results, warranting replication, robust evaluation of its efficacy, and adaptation in other settings.