This document helps stakeholders faced with brownfields that have known or suspected petroleum contamination issues learn more about these types of properties, the opportunities and challenges they present, and the ways these sites can be successfully addressed and reused. The purpose of defining and categorizing the universe of petroleum brownfields is to help identify information common to petroleum-contaminated properties and support petroleum brownfields stakeholders as they navigate the process of identification, assessment, cleanup, and revitalization of these sites. Examples of stakeholders who can benefit from this report include communities, nonprofit organizations, state and local governments, tribes, property owners and prospective purchasers, and developers and lenders. The report helps define the types of sites likely to be considered 'petroleum brownfields' and offers links to stakeholder resources and technical assistance opportunities. More specifically, this report: (1) provides a detailed description of the universe of petroleum brownfields; (2) describes and defines five categories into which petroleum brownfields can fall and the methodology used for these categorizations; (3) provides background information and relevant reuse examples across these five categories; and (4) includes comprehensive case studies for three successful petroleum brownfields reuse projects.