Health behavior interventions based on Theory of Planned Behavioraddress participants' personally-held beliefs, perceived social norms,and control over the behavior. New data are always needed to "membercheck" participants' decision processes and inform interventions. Thisqualitative study investigates decision processes around condom useamong 81 homeless LGBT youth ages 18-26. Findings indicated considerableendorsement of the conventional policy of always using condoms,promulgated in HIV prevention education targeting this population.Although some participants reported risk behavior in contexts of sexwork, survival sex, casual encounters, open relationships, and substanceuse, most were aware of these risks and consistently safe in thosesituations. Condoms use boundaries became vulnerable in states ofemotional need and negative mood. The only effect participantsacknowledged of homelessness on condom use was indirect, throughnegative mood states. The most prevalent context of condom non-use waswith long-term primary partners, a potential area of vulnerabilitybecause, of 13 participants for HIV or HCV, nine mentioned how they hadbeen infected, and all nine believed they had acquired it from a primarypartner. Findings imply programs should emphasize HIV risk potentialwithin long-term romantic partnerships and mental health services toremediate negative mood states. (Authors)