An integrated curriculum approach has been given significant place in the modern world. This is because by using this approach it is possible to overcome problems of curriculum irrelevancy, lack of connection among subjects and the issue oflalOwledge "explosion". However all these advantages are realized only when it is effectively and properly applied. Accordingly, the main purpose of this study was to assess the extent of social studies contents integration in the first cycle primary environmental science syllabus of East Showa Zone of Oromia Region. To achieve these objectives, data was collected from primary school teachers, Oromia Education Bureau curriculum department head and social science curriculum experts. The other sources of data were grades 1 t04 environmental science syllabus, environmental science student textbooks and teacher's guides. To conduct the study, descriptive survey method was employed. Random sampling technique was used in the selection of teachers and school whereas; availability sampling was employed ill selecting experts and curriculum department head. The data was collected through questiollnaire interview and content analysis of the textbooks. Percentage, frequency and mean were applied as a relevant statistical tool in analyzing the data. The findings of the study indicated that although the Educational and Training policy of the country recommends integrated curriculum for the lower primary school, in the case of social studies contents integration in environmental science syllabus, th~ policy intent has not been folly and properly realized in selected schools of East Showa Zone. Absence of essential social studies contents, I incompatibility of topics with integration principles, absence of some essential social studies skills ,presence of some difficult social studies contents in the textbooks, the dominance of traditional methods of teaching practiced by the teachers, the dominance of objective types of exercise questions that did not meet the demand of integrated curriculum, teachers unfavorable perception and low understanding towards integrated social studies contents and inadequacy of training for teachers ,curriculum experts and textbook writers were some of the findings identified as the major constraints for effective social studies contents integration in the environmental science syllabus. Based on the results of the findings the follOWing recommendations were suggested. They are revising curricular material based on integration principles, improving teachers' knowledge and skills of subject matter and methodology through in-service training and refreshment courses and offering appropriate training and orientation for textbooks writers and social studies curriculum experts