Human resources planning and workforce design decisions are an extension of traditional operations research problems, as workforce policies strive to place the appropriate and accurate numbers of the correct types of people in the right jobs at the right time. Traditional operations research methods focus on how managers oversee, design, and re-design business operations in the production of goods and/or services in efficient and effective manners. Comprehensive management methods explicitly consider human resource systems as part of these business operations. Military workforce planning and manpower modeling employs the methods and techniques of operations research to address problems of creating jobs and positions, as well as finding and assigning people to these positions. Advanced analytic techniques can also be applied to the scheduling of Soldiers or employees against shifts, optimally assigning the workforce against tasks. The variety of management issues within human resources provide opportunities to leverage simulation, optimization, economics and advanced analytics against practical problems. This chapter provides a survey of previous work in the domain along with descriptions of the fundamental mathematical models used in military workforce planning and manpower modeling useful for the military operations research practitioner and researcher. The chapter also describes two real-world case studies to highlight applications in practice.