Background: Bone homeostasis requires constant remodeling by bone-resorbing osteoclasts and bone-forming osteoblasts. Results: Choline kinase  (CHKB)-deficient mice have reduced bone mass, increased osteoclast number, and impaired osteoblast function. Conclusion: CHKB activity controls bone homeostasis via regulation of osteoclasts and osteoblasts. Significance: This is the first report implicating a role for CHKB in bone homeostasis.