This paper examines the background against which performance assessment (a new educational assessment for achievement tests) is currently being implemented in Korea. As a result, the following issues were clarified. Performance assessment within achievement tests emphasizes "high academic achievement" in terms of developing procedural (process and methodological) knowledge and problem-solving skills in actual situations (real-life and highly authentic situations). It aims to increase diversity and originality in individual thought with the advent of knowledge and information age of the 21st century. This new assessment concept is closely linked to the concept of "problem-solving skills" defined by PISA. Therefore, it can be assumed to have achieved a high level in the OECD international academic assessment. The significance of performance assessment has been recognized to an extent in terms of dealing with "guarantee of academic standards, " which the new era requires. However, although "achievement tests" have been treated in policies as a resource to "raise the academic ability of children and students who lack in basic academic abilities, " there are still many issues remaining before they can take hold in Korea.