The Sense of Community, as an important construct that supports students' participation and deep learning, has two dimensions: Social Community and Learning Community. Peer feedback is an instructional strategy employed in higher education to encourage students to assume an active role in their learning activity. The present study investigates the association between the Sense of Community and peer feedback activity in a blended university course designed according to the Progressive Design Method. This method was developed using the Knowledge Building model and incorporates peer feedback on project activities. For 30 university students of a blended course the Sense of Community was measured with the Classroom Community Scale and messages concerning the peer feedback activity in the online environment were detected and analyzed through a content analysis. Then, with a correlational research design the association between the Sense of Community and peer feedback activity was investigated. Results show a statistically significant relationship between both students' participation in online activities and the peer feedback activity with the Learning dimension of the Sense of Community. A positive relationship was found between the Learning dimension of the Sense of Community and the number of feedback messages that explained the positive aspects of the project. Also, the results demonstrate a positive relationship between the Social dimension of the Sense of Community and the number of feedback messages that offered proposals for improvement. This study and its results help to design blended university courses that promote an active role for the students and improve their Sense of Community.