Leucine-rich repeat kinase 1 (LRRK1) plays a critical role in regulating cytoskeletal organization, osteoclast activity, and bone resorption with little effect on bone formation parameters. Deficiency of Lrrk1 in mice causes a severe osteopetrosis in the metaphysis of the long bones and vertebrae bones, which makes LRRK1 an attractive alternative drug target for the treatment of osteoporosis and other high-turnover bone diseases. This review summarizes recent advances on the functions of the Lrrk1-related family members, Lrrk1 deficiency-induced skeletal phenotypes, LRRK1 structure-function, potential biological substrates and interacting proteins, and the mechanisms of LRRK1 action in osteoclasts.