A continued challenge for preservation is objective data to make informed collection decisions. When considering a shared national print system, this challenge relates to decisions of withdrawal or retention since catalog partners may not have data regarding the condition of others’ volumes. This conundrum led to a national research initiative funded by the Mellon Foundation, “Assessing the Physical Condition of the National Collection.” The project captured and analyzed condition data from 500 “identical” volumes from five American research libraries to explore the following: What is the condition of book collections from 1840–1940? Can condition be predicted by catalog or physical parameters? What assessment tools might indicate a book’s life expectancy? Filling gaps in knowledge about the physicality of our collections is helping identify at-risk collections and explain the cases of dissimilar “same” volumes based on the impact of paper composition. Predictive modeling and assessment tools are also used to improve the understanding of what is typical for specific eras.