While the concept of Web 2.0 based Personal Learning Environments (PLEs) has generated significant interest in educational settings, there is little consensus regarding what this concept means and how teachers and students can develop and deploy Web 2.0 based PLEs to support their teaching and learning activities. In this paper a conceptual framework for building Web 2.0 based PLEs is proposed. The framework consists of four main elements, including (i) student’s control model, (ii) learning potential of Web 2.0 tools and services, (iii) project-based teaching approach, and (iv) technology-enhanced learning activities. The main purpose of the framework is to assist teachers to design appropriate Web 2.0 based learning activities. Students then can accomplish these learning activities to develop their PLEs and complete their learning projects.