The present study aims to investigate whether the learning materials that based on constructivist learning principles have an effect on fifth grade Social Studies students' attitudes, their academic success and their retention. The study was conducted at Sehit Ali Gaffar Okkan Elementary School, Eskisehir. The participants of the study were 5th grade students in Sehit Ali Gaffar Okkan Elementary School. The data was collected in fall term in 2004-2005 academic year. Participants were divided into two groups: the control group (5-B) and the experimental group (5-C). In the present study, the following data collection instruments were used: a questionnaire for demographic information, pre- and post-tests and open-ended essay-type tests that were used to measure learners' academic success and retention level, lesson plans, various teaching materials for classroom activities, and a questionnaire to gather the learners' perspectives. Social Studies Attitude Scale, developed by Deveci and Guven (2002), was used to determine students' attitudes. The data obtained were analyzed using the SPSS program. The means and standard deviations were calculated for each group. The data were subjected to t-tests for inter- and between-group comparisons. The significance level was taken as 0.05. Findings of research indicate that constructivist learning principles based learning materials increase students' academic success and retention in Social Studies but don't increase attitudes. Additionally students think that constructivist learning principles based learning materials reflect constructivist learning principles. (Contains 8 tables and 2 charts.)