This study aims to analyze the effect of the formative assessment process that is implemented through the use of performance-based assessment techniques on students' achievement goal orientations. For this purpose, a mixed methods approach has been adopted. In the quantitative part of the research, a pre-test post-test quasi-experimental design have been used on experimental, placebo, and control groups. In the qualitative part of the study, a case study has been the main part. While the study group of the experimental design [Experimental (n=26), Placebo (n=27) and Control (n=27)] consists of 80 Seventh grade students, the study group of the case study consists of nine students and a teacher that has taken part in the practice. Qualitative data of the research has been collected through interview forms. While "ANCOVA", "Paired Sample t-Test" and "Wilcoxon Signed-Rank Test" have been used in the analysis of quantitative data, descriptive analysis and categorical content analysis techniques have been used in the analysis of qualitative data. The results of the study confirm that formative assessment process that is implemented through the use of performance-based assessment techniques has been partially effective on achievement goal orientations of the students.