The field of research library conservation has emerged as a distinct discipline and undergone major refinements over the past fifty years: professional organizations and training programs have been established, new treatment techniques have been developed and promoted, and, increasingly, special and general collections practitioners have collaborated on treatment solutions. Despite such dramatic growth and definition within the field, there has been no comprehensive assessment of the book treatment practices employed by research libraries for special and general collections. In response to this need, a study was undertaken to investigate and document the types of treatments employed by research libraries to conserve and maintain their book collections, and to compare the practices used for special collections with those used for general collections. This paper describes the evolution of the field over the past fifty years and identifies book conservation techniques the study found to be routinely, moderately, or rarely employed in research libraries. A comparison of special and general collections treatment practices suggests that while notable differences exist, many treatment practices are common in both contexts. Implications of the study’s results and potential applications for this new information are stated.