There is little doubt that skeletal development and subsequent maintenance of bone mass and morphology during adulthood is greatly influenced by viable muscle function. In this review, we will summarize human observations that support this concept, then focus on models that have enabled (or may enable in the future) insight into the co-dependency of muscle and bone. Specifically, we will summarize data generated with three types of models: 1) spinal cord injury models, 2) transgenic mice with altered muscle function, and 3) experimental models affecting one hindlimb or a single muscle group. In sum, these data clearly support the concept that muscle function is critical for the successful development of the skeleton and is likely to play an important role in mediating bone health through life. The specific signaling pathways by which this interdependency is achieved, however, remain to be clarified.