Bisexual women report elevated alcohol and drug use compared to other sexual minority women. This review summarized extant research on mechanisms (i.e., coping processes with minority stress and victimization, disclosure of sexual identity, connectedness to lesbian, gay, bisexual, transgender, queer, and questioning (LGBTQ+) community, religiosity, and normative perceptions) that may influence alcohol and other drug use among bisexual women. Specifically, bisexual women experience unique sexual discrimination (i.e., binegativity) and are at heightened risk for other forms of victimization and other stressful life events. Given this heightened experience with stress, bisexual women may use alcohol as a maladaptive coping mechanism. Further, disclosure of one's sexual identity may produce opportunities for connecting with the LGBTQ+ community, but such openness may increase exposure to discrimination and stigmatization among bisexual women. Findings on religiosity have been mixed, but there is some support that bisexual women may use substances in response to internal conflict between their religious beliefs and sexual identity. Lastly, we found that normative perceptions of other bisexual women's drinking behaviors are strongly tied to their own levels of alcohol use. From a therapeutic perspective, we suggest that practitioners recognize the unique experience of minority stress and teach strategies that lessen internalized stigma and promote healthy psychosocial adjustment among their bisexual clients. Clinicians may also help their clients find sources of support, which may protect them against the use of alcohol and drugs to manage minority-induced stress. Public Significance StatementBisexual women are a vulnerable population at increased risk for substance use-related harms. This review discusses underlying mechanisms (i.e., coping processes with minority stress and victimization, disclosure of sexual identity, connectedness to LGBTQ+ community, religiosity, and normative perceptions) that may be unique or contribute to substance use among bisexual women.