This book documents highlights of NASA's interactions with outside scientific advisors over the agency's full lifetime and draws lessons from that history for research managers, decision makers, and scientists.The book is divided into three parts--the first two being focused on history and the third on synthesis and analysis. Part 1 briefly examines early forerunner activities at NACA and in the decade leading up to NASA's formation, and it then considers NASA's use of outside advice during its first three decades. Part 2 picks up the story in 1988 and follows it up to 2016. Part 3 examines a sampling of case studies, discusses recurring characteristics of notably successful advisory activities, and provides a glimpse at what past experience might imply for the future of scientific advice at NASA. The last two chapters provide big-picture summaries of themes that have emerged from earlier discussions.