The aims of this research is to increase students achievement of class VIIB SMPN 10 Gorontalo City at sosial aritmetic material through problem-based instruction model with assessment of student potofolio. Procedure of this research uses classroom action research that is planning action observation and reflection at two cycles. The results of this research show that there is improvement of students learning outcomes base on criterion of minimal completeness students activity and ability of teacher manage study base on obsevation result from the first cycle to the second cycles. Base on this findings can be concluded that problem-based instruction model with assessment of student potofolio can improve the product and process learning at sosial aritmetic material.