Drabble LA, et al. - The similarities and differences in demographics and key substance use and mental health outcomes were investigated among sexual minority (SMW) and heterosexual women in probability and non-probability samples. In the non-probability sample, SMW were older, more likely to be college educated, and more likely to be in a partnered relationship compared to SMW in the probability sample. Greater odds of past-year hazardous drinking, marijuana use, and other drug use were noted in SMW in both the probability and non-probability samples compared to heterosexuals. In comparisons with heterosexual women, the magnitude of difference for drug use was greater for the SMW non-probability sample; for tobacco use, the difference was greater for the SMW probability sample. In view of the difficulties recruiting probability samples of SMW, non-probability samples in the foreseeable future will continue to be used.