This document is about identifying and describing research data sources that could be used to examine characteristics of group health plans, including whether the plans are fully insured, self-insured, or some combination thereof. It provides an overview, unit of observation, definitions, published sample statistics, data collection details, and availability for several public and private data sources such as the Kaiser Family Foundation/Health Research & Educational Trust Employer Health Benefits Survey, Medical Expenditure Panel Survey, National Compensation Survey, National Business Group on Health Annual Plan Design Survey, and Mercer's National Survey of Employer-Sponsored Health Plans.