The purpose of this report is to present a synthesis of the research on test accommodations for U.S. elementary and secondary students (K-12) published in 2018. The academic literature described here encompasses empirical studies of performance comparability, investigations into accommodations use, implementation practices, and perceptions of the effectiveness of accommodations. During 2018, 11 research studies were published on the topic of testing accommodations in the U.S. elementary and secondary education system. [For the 2017 report, see ED609703.]