The diversity of engineering education research provides an opportunity for cross-fertilization of ideas and creativity, but it also can result in fragmentation of the field and duplication of effort. One solution is to establish a standardized taxonomy of engineering education terms to map the field and communicate and connect research initiatives. This report describes the process for developing such a taxonomy, the EER Taxonomy. Although the taxonomy focuses on engineering education research in the United States, inclusive efforts have engaged 266 individuals from 149 cities in 30 countries during one multiday workshop, seven conference sessions, and several other virtual and in-person activities. The resulting taxonomy comprises 455 terms arranged in 14 branches and six levels. This taxonomy was found to satisfy four criteria for validity and reliability: (1) keywords assigned to a set of abstracts were reproducible by multiple researchers, (2) the taxonomy comprised terms that could be selected as keywords to fully describe 243 articles in three journals, (3) the keywords for those 243 articles were evenly distributed across the branches of the taxonomy, and (4) the authors of 31 conference papers agreed with 90% of researcher-assigned keywords. This report also describes guidelines developed to help authors consistently assign keywords for their articles by encouraging them to choose terms from three categories: (1) context/focus/topic, (2) purpose/target/motivation, and (3) research approach.