This chapter demonstrates the many complex client needs and barriers which impact treatment engagement, retention, and overall outcomes among LGBTQIA (lesbian, gay, bisexual, transgender, queer, questioning, intersex, asexual and ally) clients. The assessment process is usually the first encounter with the client. The ongoing need to address co-occurring behavioral health problems is a high priority for the social work profession. Addressing gender identity and expression in behavioral health treatment acknowledges the differences that may play a role in the overall clinical picture for those that identify as gay, bisexual, lesbian, transgender, and queer. Social workers must be attentive to feelings of shame, doubt, and confusion in clients affected by anti-LGBTQIA discrimination, stigma, and prejudice. Cognitive behavioral therapy approaches are encouraged to address stress associated with the coming out process, acceptance or emotional distress common among LGBTQIA clients, and for addressing many other mental health concerns such as self-esteem and self-worth.