The most exciting recent advances in skeletal growth factor biology have emerged from genetic and transgenic approaches, and these have greatly enhanced our understanding of the role played by growth factors in the developing and adult skeleton. A more coherent picture of the interplay between different hormones, growth factors, and cytokines during the development of cartilage and bone is emerging. With the advent of inducible and tissue specific knockout and transgenic animal models, investigating actions of growth factors in the adult skeleton has begun separately from their role in development. The development of parathyroid hormone (PTH) as a bone anabolic and approved treatment for osteoporosis has triggered a flood of detailed mechanistic studies, which are already highlighting the central involvement of growth factors in orchestrating some of the effects of this therapy. There are many open questions, particularly relating to the actions of growth factors on ostoclasts and on mature articular chondrocytes. Continued research into the skeletal growth factors will open up their use as anabolic and repair agents for bone and cartilage. © 2006 Elsevier Inc. All rights reserved.