Melodramas are sometimes called "tearjerkers" because of their ability to make viewers cry, but there is currently no detailed account of how they succeed at this task. Psychological research suggests that crying occurs when people feel helpless in the face of intense emotion. The emotion felt most intensely when watching melodramas is sadness, and sadness has a structure and specific features that determine its intensity. I describe the ways the conventions of melodrama fulfill the criteria for intense sadness and perceived helplessness that underlie these films' ability to make viewers cry. I illustrate this model with a detailed analysis of Stella Dallas (1937).