Real-world condensed phases usually exhibit both solid-like (elastic) and fluid-like (viscous) behaviors. Examples include tooth pastes, honey and cornstarch suspensions. Crystals and ideal liquids have been relatively well studied. Viscoelastic materials are, however, more challenging. Moreover, many biological fluids, such as biofilms, cytoplasm, and bacteria suspensions, are active in the sense that chemical energy is converted into locomotion of motor proteins or bacteria, rendering the system in a nonequilibrium state. In this project, we seek to understand and model a range of active viscoelastic materials using particle-based and continuum simulations. Through the development of active viscoelastic models, we will be able to reproduce biofluids phenomena and make predictions that await future experimental work.