Lab-based follow-up will occur at 3- and 6-months postpartum. The primary outcomes will be participant report of frequency of substance use and toxicological analyses of substance use (urinalysis and expired breath CO at 3 and 6 month follow-up, hair analysis at 6-month follow-up). Secondary outcome measures include HIV risk behaviors, receipt of treatment services, motivation to change, self-efficacy, mental health functioning, violence exposure, and consequences related to substance use.