Engineered tendon fibroblast and collagen-based soft tissue constructs have been developed to characterize growth and remodeling in soft tissue via in vitro studies of the effects of controlled mechanical interventions on collagen content and orientation. Growth and remodeling often occur simultaneously in soft, tissue. The present contribution distinguishes these separate biological processes and develops the theoretical frameworks for the formation of constitutive theories of each. Remodeling is considered as a motion in material space that occurs at constant mass whereas growth is a change in concentration due to mass transport and is treated via a system open with respect to mass. Examples illustrating both biological processes are presented.