Heavy substance users present challenges to traditional forms of medical and mental health care. This project considers several areas of overlap among substance users, addictions treatment, and psychiatric care as delivered in the emergency department (ED). Suicide may be conceptualized as an "acute" moment of crisis in the context of chronic distress. In the ED, chronic social and psychiatric problems must be conceptualized as acute episodes of illness. The role of the ED was considered retrospectively, in order to determine how its importance is conceptualized and incorporated after the fact. Chapter 1 reviews the participants and setting, methods and analysis, and four broad areas of literature relevant to the project. Chapter 2 demonstrates that the ED is a transitional setting whose purpose differs for patients, providers, and outside clinicians. Chapter 3 examines substance users' subjective experience of feeling suicidal, in order to contextualize the crisis of suicide within a framework of chronic of distress. Chapter 4 shows how substance users learn to speak a less messy, but also less accurate, language of suicidality to ED providers, and the extent to which beliefs about suicide are internalized through this process. Chapter 5 focuses on a psychiatric diagnosis, bipolar disorder, which was nearly ubiquitous among the substance users interviewed for this project. Given its widespread presence, the diagnosis itself suggests an important story about the pressure to give chronic problems an acute gloss. Chapter 6 widens the scope of the acute/chronic divide to explore how an addictions treatment agency managed an acute financial crisis. Mental health professionals within this agency were pressured to draw new lines around what constituted "emergencies," and the importance of the ED grew in response. The concluding chapter argues that in spite of formidable obstacles, the ED offers advantages that would be hard to replicate in other care settings.