This volume aims at providing readers with protocols to enhance their research for the next decade of phytochrome research. The chapters in this book cover topics such as tests for light-dependent interaction of phytochrome binding proteins using yeast two hybrid assays, in vitro pull down, and co-immunoprecipitation from stable transgenic lines; investigations into phosphorylation, SUMOylation, and ubiquitination of phytochromes and other proteins; a look at how in vivo spectroscopy can be used to measure Pfr levels of phytochrome in planta; identifying hormonal action and co-action in light-regulated processes; and ways to use the CRISPR/Cas9 system to generate Physcomitrella mutant lines. 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. Cutting-edge and comprehensive, Phytochromes: Methods and Protocols serves as a guideline to researchers who are new to the field, and a stepping stone for experienced researchers looking to expand their knowledge of this evolving field.