Mandates that follow from the No Child Left Behind Act (NCLB, 2002) led to changes to curriculum and classroom instruction. Teachers felt pressured to alter their curriculum and instructional practices. To ensure that students receive a quality education, teacher perceptions of instructional assessment and curriculum is of paramount concern, especially for low versus high socioeconomic-status (SES) districts. The research questions for this study examined whether teachers employed in low SES districts differed from teachers employed in high SES districts on the pressures felt and the perceived effects of state tests on curriculum and instruction. The purpose of the study was to determine whether teacher perceptions differed by districts. The theory of reasoned action, which posits that a person's perceived control over his or her behavior is predictive of his or her behavioral intention, served as the theoretical foundation. A non-equivalent group design was used. The Elementary Teacher Questionnaire was completed by 166 teachers. Results of independent samples t-test, indicated that teachers employed in low SES districts felt more pressure from administrators and made more changes to curriculum and instruction than teachers employed in high SES districts. This study contributes to social change by identifying differences in curriculum and instructional delivery in varying SES level districts as they implement state assessments. Several implications for positive social change include: (a) providing information for formulating testing accountability policies in school districts, (b) the need for application of best practices in content teaching, (c) recommending a more equitable system to include multiple criteria of student achievement, and (d) the need for statewide assessment accountability systems to be reconsidered and evaluated under NCLB. [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.]