This article introduces the concept of social constraints on disclosure, puts it in a theoretical framework, and examines how it can affect adjustment to major life stressors using the exemplar of cancer. Cancer is a leading cause of death and disability worldwide. It is often life threatening, disfiguring, and unpredictable; hence, it can undermine people's basic and often positive beliefs and expectations about themselves, their future, and social relationships. For many people with cancer, it is important to come to terms psychologically with the illness – to make sense of or somehow accept the reality of it. People often do this by thinking about different aspects of the disease and its implications for their life, but also through socially processing, or talking about, their cancer-related thoughts, feelings, and concerns with others. When people experience social constraints on their disclosure of cancer-related thoughts and feelings, it can adversely affect how they think and talk about their illness, their coping behaviors, and psychological adjustment. In addition to discussing mechanisms and consequences of social constraints on disclosure, we discuss some of its determinants and future research directions.