This code provides retrofit and rehabilitation criteria for reinforced concrete buildings based on results from the most recent research on the seismic performance of existing concrete buildings. The intent of this code is to provide provisions related to concrete material and concrete members, including material testing criteria, modeling parameters, and acceptance criteria for use within the ASCE 41 framework, similar to how the National Earthquake Hazards Reduction Program (NEHRP) Recommended Seismic Provisions produced by the Federal Emergency Management Agency (FEMA) (FEMA 450) have served as source documents for the International Building Code (IBC) and its predecessor building codes. Starting in the 2023 edition, ASCE 41 references ACI 369.1 directly for concrete-related provisions. Chapter and section numbers of ASCE 41 cited in ACI 369.1 correspond to ASCE 41-17 unless otherwise noted.