The reproductive health needs of women with substance use disorders (SUDs) are unmet. Over 80% of pregnancies among women with SUDs are unintended, compared to 45% of the general population, and over 20% of women with SUDs have had a short interpregnancy interval (i.e. pregnancy within 18 months of a previous birth). Pregnancy is a unique opportunity to address contraceptive needs due to increased healthcare access from expanded Medicaid eligibility, increased access to highly effective contraceptive methods such as long-acting reversible contraception (LARC) and enhanced motivation to avoid rapid, repeat pregnancy. Despite this, over 75% of women with opioid use disorder fail to use postpartum contraception and less than 2% receive LARC in the postpartum period. Currently, there are no effective strategies to improve postpartum contraceptive decision-making for women with SUDs. To address this gap, we will conduct a hybrid type 1 effectiveness- implementation randomized controlled trial among 350 postpartum women with SUDs to test the effect of a novel patient-centered, reproductive planning decision support tool, developed by the research team, called MyPath on postpartum contraceptive method choice and continuation, continuous contraceptive use, unintended pregnancy and interpregnancy interval until 18 months postpartum. The primary research aims are to 1) assess the effect of patient-centered, reproductive planning decision support (MyPath) on postpartum contraceptive utilization and reproductive health outcomes among women with SUDs; 2) determine if the relationship between MyPath and contraceptive utilization is mediated by decision quality; and 3) identify barriers and facilitators to integrating MyPath into routine postpartum clinical care. This research is significant because using a patient-centered, reproductive planning approach to contraceptive decision-making represents a paradigm shift in both how we frame and approach reproductive health outcomes among women with SUDs. Our findings will have high impact if successful as decision support tools are a low-cost, scalable solution that can be used in most clinical settings and our study design enhances the potential for rapid translation of our findings into routine clinical practice. Finally, it is feasible because it builds on prior work by a research team with expertise in decision sciences, implementation, family planning, obstetrics and SUDs.