Objectives: Alcohol and substance misuse has been under-acknowledged and underidentified in older adults. However, promising treatment approaches exist (e.g., brief interventions) that can support older adults with at-risk alcohol and substance use. Postacute rehabilitation settings of Skilled Nursing Facilities (SNFs) can offer such programs, but little is known about patient characteristics that are associated with the likelihood of participating in interventions offered in postacute rehabilitation care. Thus, the objective of this study was to identify individual patient characteristics (predisposing, enabling, and need-related factors) associated with participation in a brief alcohol and substance misuse intervention at a SNF. Methods: This cross-sectional study analyzed medical record data of postacute care patients within a SNF referred to a substance misuse intervention. Participants were 271 patients with a history of substance misuse, 177 of whom enrolled in the intervention and 94 refused. Data collected upon patient admission were used to examine predisposing, enabling, and need-related factors related to likelihood of program participation. Results: Older age and ethnic minority status were associated with a reduction in likelihood to participate, while widowhood increased the likelihood of participation. Conclusion: Upon referral to a substance misuse intervention, clinicians in SNFs should be cognizant that some patients may be more likely to refuse intervention, and additional efforts should be made to engage patients at-risk for refusal.