TARGET-NASH is a longitudinal observational cohort study of patients being managed for NASH or NAFL in clinical practice. TARGET-NASH will create a carefully maintained, actively monitored research registry of patients with NAFL or NASH within academic and community real-world practices in order to assess the safety and effectiveness of current and future therapies. The study is designed to rapidly inform strategies for better management of populations underrepresented in clinical trials including children, and to identify and remediate educational gaps relative to treatment guidelines and adverse event management. The goal is to identify the factors associated with favorable versus suboptimal clinical response in a real world clinical practice setting, and serve as the core resource for important collaborative translational studies utilizing bio specimens and clinical data from diverse patient populations. Thus, the aim of this longitudinal observational study is to establish a large, diverse registry of patients with NAFL or NASH at both academic and community practices that can be leveraged to improve the health and reduce the development of cirrhosis and liver cancer in such patients.