The summary plan description (SPD) is the primary source of information for workers who participate in an employment-based health care plan. This paper investigates whether private-sector employers' SPDs are written so that an average plan participant can identify and read important information contained in the document, as required by federal law. Summary plan descriptions for 40 health care plans from a diverse national sample were collected and tested and subjected to content and readability analyses. The data from this study provide quantifiable evidence about whether summary plan descriptions cover the necessary topics that participants need to know about their health plans, and the educational level required to read them.