This volume presents a collection of protocols that describe methodologies to study thermogenic fat biology from various angles. This book is divided into 2 parts. Part 1 focuses on establishing in vitro culture systems. The chapters in this section introduce techniques on how to isolate, culture, and differentiate primary fat cells from both laboratory mice and humans. This part also presents flow cytometry methods to isolate various subpopulations of precursors within the stromal vascular fraction of the adipose tissue, which contains both preadipocytes and immune cells. Part 2 introduces multiple means to genetically manipulate and evaluate brown and beige fat in vivo. The chapters in this section explore methods on bioenergetics analyses both in vitro and in vivo. They also cover how to evaluate thermogenic fat contents and activity in humans, how to culture these cells though interdisciplinary approaches, and how to use thermogenic fat cell lines to carry out drug screens. Written in the highly successful Methods in Molecular Biology series format, chapters include introductions to their respective topics, lists of the necessary materials and reagents, step-by-step, readily reproducible laboratory protocols, and tips on troubleshooting and avoiding known pitfalls. Thorough and cutting-edge, Thermogenic Fat: Methods and Protocols is a valuable resource for both experts and novices who are interested in learning assays and investigating brown and beige fat functions.