This article describes challenges, issues, and strategies associated with public health workforce research. The factors that contribute to workforce supply and demand imbalances are reviewed, and the unique difficulties encountered with studies of public health workers are identified. Two case studies of previous public health workforce research conducted by the New York Center for Health Workforce Studies are used to illustrate how different levels of analyses can be used to better understand recruitment and retention issues of public health workers and to inform programs and policies designed to ensure a well-sized and competent public health workforce. Case study 1, conducted in 2005, assessed supply and demand gaps in state and local health departments in six states and helped estimate the scope of recruitment and retention problems in these agencies. Case study 2, conducted in 2006, provided a detailed examination of the current public health workforce in local health departments in New York. Data drawn from this study were used to identify specific workforce challenges faced by these agencies. Findings from these case studies, conducted at different levels of analyses (multistate vs single state) and using different research methods (qualitative vs quantitative), are reviewed, highlighting differences based on scope and methods. Finally, suggested areas for future studies about the public health workforce are considered.