The paper is devoted to the issue about the functioning of a common system for assessing the education quality and its improvement in Latvia. The aim of the paper is to compare the results gained in the OECD PISA study with the assessment data on the quality of Latvian national general education and the indicators characterizing the school. The research question is to explore the relationship between the results of students’ achievement in PISA 2006 and the results of Grade 9 students in the national examinations in mathematics, state (Latvian) language and natural sciences (in particular, the authors will use the examination in mathematics, the examination in the Latvian language for the Latvian as the mother tongue curriculum, the centralized examination in the Latvian Language for minority educational programs and the test in natural sciences). The paper will also study the dependence of students’ achievement on the indicators of school funding (funding per one pedagogical fulltime load and funding per student), the number of students at school per one pedagogical fulltime load and other socioeconomic indicators of the school and family, using the statistic data on education in Latvia and the data from PISA study. The study will use the methods of descriptive statistics, including the correlation and linear regression methods. Finally, at the end the authors will provide the evaluation of the correspondence between the results of the international and state measurements of the education quality. In case of need, the recommendations for improving the procedures of implementing the state examinations and other recommendations for the policy makers concerning a common monitoring system of education quality in Latvia will be worked out.