US and China are reforming mathematics teaching by shifting from students' attainment of facts and procedures toward development of competencies in reasoning, communication, connections, and problem solving, and application of these in real life contexts. Differences in students' overall performance, curricula, and teachers' knowledge and instruction between US and Eastern Asian countries are often used to support US reform with two obvious limitations. First, their performance has not been delineated into specific areas which raise questions about whether overall higher Asian mathematics performance over US is also evident in the specific US reform competencies. Second, Asians are often used as an indiscriminate group with inattention to different schooling and non-schooling factors between countries that might contribute differently to performances. This meta-analysis examines US and Chinese student mathematics performance studies and identifies the strengths and weaknesses in overall and specific competencies. It raises questions about theoretical assumptions, discusses limitations of research designs, and proposes research that may lead to a critical understanding of the quality of mathematics learning. (Contains 7 tables.)