Mathematical achievement and interest has declined in the United States as evidenced through national and international assessments. Students were not entering mathematics and science-related fields, even though these fields were the fastest growing industries worldwide. This study examined the effects an integrated Science, Technology, Engineering, and Mathematical (S.T.E.M.) curriculum in its first year had on fourth grade students' mathematics achievement and attitudes toward mathematics. The sample for the achievement variable consisted of 1,754 fourth grade students; 70 fourth grade students served as the sample for the attitude variable. The researcher collected two sets of quantitative data: third and fourth grade mathematics Tennessee Comprehensive Achievement Program scores and pre- and posttest Likert attitude scales. The results were mixed. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]