With states weighing whether to adopt the Next Generation Science Standards (NGSS), this analysis from the Thomas B. Fordham Institute compares the existing science standards of thirty-eight states with the NGSS and with exemplary standards from three other states. The K-12 science standards were compared for states whose expectations were either "too close to call" or "clearly inferior to" those of the NGSS with the expectations set by three of the top-performing states, as well as with the Next Generation Science Standards themselves. Comparisons are presented side-by-side in the form of brief descriptions of the quality of the standards, including salient strengths and weaknesses. Five areas are covered: (1) treatment of scientific inquiry and practices; (2) physical science (including physics and chemistry); (3) life science; (4) earth and space science; and (5) clarity and specificity. [Introduction by Chester E. Finn, Jr. and Kathleen Porter-Magee.]