Abstract Background To conduct a systematic assessment of library and informatics training at accredited Western U.S. medical schools. To provide a structured description of core practices, detect trends through comparisons across institutions, and to identify innovative training approaches at the medical schools. Methods Action research study pursued through three phases. The first phase used inductive analysis on reported library and informatics skills training via publicly-facing websites at accredited medical schools and the academic health sciences libraries serving those medical schools. Phase Two consisted of a survey of the librarians who provide this training to undergraduate medical education students at the Western U.S. medical schools. The survey revealed gaps in forming a complete picture of current practices, thereby generating additional questions that were answered through the Phase Three in-depth interviews. Results Publicly-facing websites reviewed in Phase One offered uneven information about library and informatics training at Western U.S. medical schools. The Phase Two survey resulted in a 77% response rate. The survey produced a clearer picture of current practices of library and informatics training. The survey also determined the readiness of medical students to pass certain aspects of the United States Medical Licensure Exam. Most librarians interacted with medical school curricular leaders through either curricula committees or through individual contacts. Librarians averaged three (3) interventions for training within the four-year curricula with greatest emphasis upon the first and third years. Library/informatics training was integrated fully into the respective curricula in almost all cases. Most training involved active learning approaches, specifically within Problem-Based Learning or Evidence-Based Medicine contexts. The Phase Three interviews revealed that librarians are engaged with the medical schools' curricular leaders, they are respected for their knowledge and teaching skills, and that they need to continually adapt to changes in curricula. Conclusions This study offers a long overdue, systematic view of current practices of library/informatics training at Western U.S. medical schools. Medical educators, particularly curricular leaders, will find opportunities in this study's results for more productive collaborations with the librarians responsible for library and informatics training at their medical schools.