Murine MC3T3‐E1 and MC‐4 cells were stably transfected with −371/+70 bp of the murine cyclooxygenase‐2 (COX‐2) promoter fused to a luciferase reporter (Pluc371) or with Pluc371 carrying site‐directed mutations. Mutations were made in (1) the cAMP response element (CRE) at −57/−52 bp, (2) the activating protein‐1 (AP‐1)–binding site at −69/−63 bp, (3) the nuclear factor of activated T‐cells (NFAT)–binding site at −77/−73 bp, and (4) both the AP‐1 and NFAT sites, which comprise a composite consensus sequence for NFAT/AP‐1. Single mutation of CRE, AP‐1, or NFAT sites decreased parathyroid hormone (PTH)–stimulated COX‐2 promoter activity 40% to 60%, whereas joint mutation of NFAT and AP‐1 abrogated the induction. On electrophoretic mobility shift analysis, PTH stimulated binding of phosphorylated CREB to an oligonucleotide spanning the CRE and binding of NFATc1, c‐Fos, and c‐Jun to an oligonucleotide spanning the NFAT/AP‐1 composite site. Mutation of the NFAT site was less effective than mutation of the AP‐1 site in competing binding to the composite element, suggesting that cooperative interactions of NFATc1 and AP‐1 are more dependent on NFAT than on AP‐1. Both PTH and forskolin, an activator of adenylyl cyclase, stimulated NFATc1 nuclear translocation. PTH‐ and forskolin‐stimulated COX‐2 promoter activity was inhibited 56% to 80% by calcium chelation or calcineurin inhibitors and 60% to 98% by protein kinase A (PKA) inhibitors. These results indicate an important role for the calcium‐calcineurin‐NFAT signaling pathway in the PTH induction of COX‐2 and suggest that cross‐talk between the cAMP/PKA pathway and the calcium‐calcineurin‐NFAT pathway may play a role in other functions of PTH in osteoblasts. © 2010 American Society for Bone and Mineral Research