This study aims at investigating the effect of cooperative learning model type STAD on learning interest and social study learning achievement of fourth grade students of Primary School Number 3 Legian, Kuta, Badung in the academic year 2012/2013. This research was quasi-experiment of The Posttest-Only Control Group Design involving 60 students of Primary School Number 3 Legian, Kuta, Badung as the sample of the research. The instruments used for collecting the data were social study learning achievement test and learning interest questionnaire. The collected data were analyzed using MANOVA. The results of the analysis are as follows. First, the social study learning achievement of students following cooperative learning model type STAD is better than those following conventional learning model. Second, the learning interest of students following cooperative learning model type STAD is better than those following conventional learning model. Third, the social study learning achievement and learning interest of students following cooperative learning model type STAD is better than those following conventional learning model.