Cystic fibrosis has traditionally been conceptualized as a fatal childhood disease. In contrast, survival age has been increasing steadily such that adults now routinely seek to gain employment and form close relationships, situations that might require telling others about the disease. Here, the author examines three situations of disclosure based on interviews with 31 adults with the disease. First, in a low-risk situation, for example a short period of social contact, a low level of intimacy exists between the adult with cystic fibrosis and another. Here the disease may be concealed easily with little risk of discovery. Second, in a medium-risk situation, the perceived reaction of the other begins to influence the decision to disclose, as the level of intimacy becomes higher. Last, in high-risk situations, such as employment, the consequences of disclosing or concealing CF are most severe. However, a multiplicity of factors, including perceived social support and disease progression, are seen to influence adults’ decisions to disclose their disease.