Four primary tasks were conducted for this two-phase study, which examined the outcomes to challenged library materials in terms of retention, restriction, and removal, and identified key factors that influenced the outcome: (1) the relevant research literature was reexamined and a conceptual model for testing based on the research literature was reviewed; (2) a stratified random sample of 6,557 secondary schools was produced; (3) a one-page questionnaire was sent to the school librarians to identify schools that had received a challenge to library materials (complaint) within a 3-year period; and (4) a second, detailed questionnaire designed to test the conceptual model was sent to the librarians who reported having received one or more challenges to obtain data on the most recently resolved challenge. Of the 4,736 questionnaires (72%) for the first stage of the survey that were completed and returned, 2,964 reported no complaints, and 1,661 reported one or more complaints. The response rate for the second stage was 70%, with 1,171 questionnaires returned. This questionnaire elicited information on the factors included in the model, i.e., the district materials selection policy, characteristics of the librarian, school environment, community environment, initiator of the challenge, and complaint background. Factors which were found to be significant in influencing the retention of challenged library materials in secondary public school libraries were the existence and use of a board approved materials selection policy, internal and external support provided to the librarian during the challenge, overall support for the retention of challenged material, and the form of complaint, with written complaints being more likely to result in retention than oral complaints. The findings reported in the literature are discussed with the findings of this study throughout the report, and a long-term replication of this study is recommended. Additional data and copies of the questionnaires are presented in 11 appendices. (34 references) (MAB)