By means of data from the most comprehensive source of teacher data in the nation, Schools and Public School Teacher Staffing Survey (SASS), we designed a follow-up quantitative study to test the effects of two decades of national policy mandates on instructional time allotments for core academic subjects. We used data from the SASS data from National Center for Educational Statistics (NCES) (1993/1994, 1999/2000, 2003/2004, 2007/2008) to examine national trends of continued marginalization of social studies by exploring the influence of recent educational policy on defining elementary curricula in the 21st Century. With the reauthorization of NCLB in 2007 and newly mandated science testing in grades 3 through 5, we sought to understand statistically how this policy change has affected instructional decisions regarding time allocated to core academic subjects (ELA, mathematics, science and social studies) in elementary schools. Findings provide evidence of the national trend of the declining role of social studies in an era in which testing is associated with importance. Moreover, grade level disparities unique to social studies intensified the effects of 2007 NCLB policy mandates of science testing for 3rd through 5th grade students. Results provide a broader and nationally generalizable understanding of the declining role of social studies in elementary schools and the reduction of time practitioners spend teaching social studies. Thus, the growing imbalance in instructional time distributions for social studies and the tipping of the time distribution scales in favor of science document teacher responses to the expansion of testing mandates and the continued absence of studies from the national testing landscape. (Contains 3 tables, 8 figures and 1 footnote.)