Osteocytes are multifunctional bone cells that act as modulators of mineralized matrix resorption. They reside in small cavities of bone called lacunae and form an extensive canalicular network of dendrites (lacuno-canalicular network, LCN) for cell-cell interaction. Bones from mice with X-linked hypophosphatemia (Hyp), which have impaired production of 1,25 dihydroxyvitamin D (1,25D), demonstrate abnormal LCN organization, with enlarged lacunae, impaired canalicular structure, and enhanced osteocyte expression of bone resorption genes compared to WT. Administration of 1,25D or an anti-FGF23 targeting antibody to Hyp mice improves LCN organization, supporting a role for 1,25D in regulating LCN remodeling. In support of this, bones from mice lacking the vitamin D receptor (VDR) in osteocytes (VDRf/f;DMP1Cre+) have impaired LCN organization compared to control, demonstrating that osteocyte-specific actions of 1,25D regulate LCN remodeling. In osteoclasts, the transcription factor nuclear factor of activated T cells cytoplasmic 1 (NFATc1) induces the expression of matrix resorption genes to acidify the extracellular environment and enhance bone resorption. Since osteocytes also acidify their microenvironment and resorb matrix, we hypothesize that NFATc1 plays a role in 1,25D-mediated LCN remodeling. Consistent with this hypothesis, 1,25D suppresses Nfatc1 mRNA expression in IDG-SW3 osteocytes, and knockdown of Nfatc1 expression by lentivirus carrying anti-Nfatc1 shRNA in IDG-SW3 cells attenuates the 1,25D-mediated suppression of matrix resorption gene expression and blocks the 1,25D-mediated suppression of RANKL-induced acidification of the osteocyte microenvironment. These data show that NFATc1 is required for 1,25D-mediated regulation of perilacunar remodeling in vitro. Corresponding with the in vitro data, VDRf/f;DMP1Cre+ osteocytes have enhanced Nfatc1 and matrix resorption gene expression. To determine the role of NFATc1 in 1,25D mediated LCN remodeling, histomorphometric analyses of tibiae from mice lacking osteocyte-specific NFATc1 (NFATc1f/fVDRf/f;DMP1Cre+) were performed, demonstrating that bones from these mice have decreased lacunar size associated with normalized expression of matrix resorption genes, decreased immunoreactivity for matrix resorption marker cathepsin K, and improved canalicular structure compared to VDRf/f;DMP1Cre+ control. Taken together, the current study demonstrates that NFATc1 is necessary for 1,25D-mediated regulation of osteocyte LCN remodeling.