The main purpose of this legislation is to simplify the process for constructing infill housing by exempting certain federal actions from the requirements of the National Environmental Policy Act (NEPA) of 1969. This act aims to encourage the development of residential housing in urban areas that are underutilized or vacant, thereby addressing housing shortages. Key provisions of the legislation include the definition of "infill housing" and the specific conditions under which federal actions related to its construction are exempt from NEPA.