Liaison roles are generally commonplace in medical and health sciences libraries as librarians strive to develop and enhance relationships and collaborations with clinicians and faculty. While the liaison of the past acted primarily as the main contact between respective departments and the library providing a facilitative function (e.g. arranging for instruction sessions, inviting feedback on the collection, providing updates on new programs and services, etc.), today’s liaison activities are more proactive and robust. The Engaged Health Sciences Library Liaison features ten program descriptions that illustrate how the reach and scope of librarians in the medical/healthcare arena has changed dramatically since the inception of liaison services. The program outcomes described: illustrate a direct impact on curriculum development, address new information types with new access and preservation technologies, expand stakeholder groups, create research and teaching collaborations, and enhance functional roles. This authoritative book copublished by the Medical Library Association demonstrates that collaboration and communication, the basic tenets of a liaison program, breed innovative programs and services that are relevant, current, and valuable.