A pilot trial (N=60) will be conducted to test the feasibility and preliminary effectiveness of OnTrack (a smartphone application to self-monitor substance use and sexual behaviors among homeless young adults) plus a brief motivational intervention (BMI), in comparison to treatment as usual (TAU) at Covenant House New York (CHNY) for those with substance abuse problems and who engage in risky sex. Following referral, screening, and eligibility determination, 60 participants will complete informed consent and be randomly assigned to one of two conditions: 1) TAU or 2) OnTrack + BMI. All participants will be assessed at baseline, 2 weeks, 4 weeks, and 6 weeks after baseline to evaluate alcohol consumption, marijuana use, HIV sexual risk behaviors, and other relevant variables.

Homeless young adults have high rates of substance abuse and HIV infection and, therefore, developing effective, acceptable, and sustainable interventions to reduce their substance abuse and sexual risk behaviors is of high public health significance.

HealthCall for Smartphone (HealthCall-S) is a smartphone application originally designed for self-monitoring of alcohol use and other HIV-related health behaviors, and receiving personalized feedback on these behaviors among urban substance-abusing HIV primary care patients. Building upon prior HealthCall-S studies, individual qualitative interviews were conducted with 10 homeless young adults (age 18-21 years) at Covenant House New York (CHNY), the largest provider of crisis shelter and services for homeless young adults (age 18-21 years) in NYC. The purpose of the individual interviews was to obtain reactions to various aspects of HealthCall-S and determine how it could be adapted to better suit the needs and interests of homeless young adults. HealthCall-S has since been adapted to target alcohol use, marijuana use, and sexual risk behaviors among homeless young adults and renamed 'OnTrack.' A pilot trial (N=60) will be conducted to test the feasibility and preliminary effectiveness of OnTrack plus a brief motivational intervention (BMI), in comparison to treatment as usual (TAU) at CHNY for those with substance abuse problems and who engage in risky sex. Following referral, screening, and eligibility determination, 60 participants will complete informed consent and be randomly assigned to one of two conditions: 1) TAU or 2) OnTrack + BMI. All participants will be assessed at baseline, 2 weeks, 4 weeks, and 6 weeks after baseline to evaluate alcohol consumption, marijuana use, HIV sexual risk behaviors, and other relevant variables.

Inclusion Criteria:

• 18-21 years of age
• Engaged in unprotected vaginal, anal, or oral sex in the past year
• Drank alcohol in the past year
• Used marijuana on 4 or more days in past month

Exclusion Criteria:

• Actively psychotic, suicidal, or homicidal
• Does not speak English
• Has a vision/hearing impairment that would preclude participation
• Has definite plans to leave the greater New York metropolitan area within the study period