AbstractMuscle stem cells (MuSCs) are essential for maintaining muscle homeostasis by providing progenitor cells for muscle regeneration after injury and in muscular diseases. MuSC properties dynamically change, reflecting physiology or pathological status. For instance, MuSCs are activated after muscle injury, but become exhausted in late stages of Duchenne Muscular Dystrophy (DMD) disease and senescent during aging. Therefore, characterization of MuSCs, including proliferation, activation, senescence, and apoptosis, etc., is very important in applying MuSC knowledge to regenerative medicine, such as in the treatment of DMD and to improve muscle function in aging. Here, we describe a detailed method for characterizing MuSCs in situ using immunostaining techniques in the mouse. This method can also be easily adapted to analyze other skeletal muscle properties. © 2018 by John Wiley & Sons, Inc.