This document discusses the importance and benefits of library collaboration. It provides definitions of cooperation, collaboration, and deep collaboration. Deep collaboration involves substantial commitment from organizations to achieve common goals through shared authority, responsibility, and resources. Examples of successful library collaborations discussed include the Digital Public Library of America, which provides access to millions of digital items, and Minnesota Reflections, which allows smaller institutions to contribute local history collections. The document suggests that collaboration provides gains in efficiency, services, resources that outweigh the costs and productivity losses of working together. Key factors for successful collaborations include having the right participants, clear goals, adequate resources, and support services. Respondents to a survey note benefits of shared costs, knowledge, resources, and