Computational modeling in biomechanics has become a standard methodology, both for interpreting the biomechanical and biophysical basis of experimental results and as an investigative approach in its own right when experimental investigation is difficult or impossible. The finite element (FE) method is by far the most common numerical discretization and solution technique that has been used. However, the lack of a software environment that is tailored to the needs of the field has hampered research progress, dissemination of research and sharing of models and results. To address these issues, over the initial funding period, we developed FEBio, a nonlinear implicit FE framework designed specifically for analysis in biomechanics and biophysics. In this competing continuation application, we propose to considerably expand the capabilities of FEBio - to model the biomechanics and biophysics of living tissues by capitalizing on recent advances in the continuum mechanics of reactive mixtures. We also propose to broaden the target audience of FEBio by creating tools that facilitate interfacing with custom code. To help optimize the computational costs associated with these advanced modeling techniques, we also propose to extend the application of parallel processing in FEBio beyond the solver routines. Applications of computational biomechanics and biophysics span all fields of the biomedical sciences, including areas as diverse as molecular dynamics, cell motility and mechanics, cardiovascular mechanics, musculoskeletal biomechanics and tissue engineering. The FEBio software suite will facilitate advances in these fields, which in turn will contribute to improved understanding o basic biological and medical questions as well as improved strategies for diagnosis and treatment of disease. PUBLIC HEALTH RELEVANCE: Applications of computational biomechanics span all fields of the biomedical sciences, including areas as diverse as molecular dynamics, cell motility and mechanics, cardiovascular mechanics, musculoskeletal biomechanics and tissue engineering. The FEBio software suite will facilitate advances in these fields, which in turn will contribute to improved understanding of basic biological and medical questions as well as improved strategies for diagnosis and treatment of disease.