The present invention provides compositions and methods for modulating the growth, development, and repair of bone, cartilage, or other connective tissue. Also provided are devices and stimulation waveforms to differentially modulate the behavior of osteoblasts, chondrocytes, and other connective tissue cells to promote proliferation, differentiation, matrix formation, or mineralization for in vitro or in vivo applications. Continuous mode and pulsed segment mode of cell stimulation with charge-balanced signals can be used. Bone, cartilage, and other connective tissue growth is stimulated in part by the release of nitric oxide via electrical stimulation, and can be regulated by simultaneous supply of NO donors and NO synthase inhibitors. Bone, cartilage and other connective tissue growth is stimulated in part by the release of BMP-2 and BMP-7 in response to electrical stimulation that promotes cell differentiation. The methods and devices are useful for promoting bone fracture repair, cartilage and connective tissue repair, and for engineering tissue for transplantation.