Constructivism is a theory of knowledge, based on observation and scientific study of how people learn. It states that people construct their own understanding and knowledge of the world, through experiencing things and reflecting on those experiences. When we encounter something new, we have to reconcile it with our previous ideas and experiences, either changing what we believe, or discarding the new information as irrelevant. In any case, we are active creators of our own knowledge. Because all learning is filtered through our pre-existing knowledge, constructivists suggest that learning is more effective when a student is actively engaged in the learning process rather than attempting to receive knowledge passively.The book explains the need for constructivism and answers various questions regarding the justification of epistemological and logistic evolution of constructivism. It studies various pathways in constructivism and how they facilitate acquisition of knowledge in different domains. Conceptual changes in the basic process of constructivism and concept map and constructivism, have been dealt with in exclusive chapters. A learner-centered input-output model and some important teaching models along with the respective frameworks thereof have been explained with examples. Various roles of a teacher and mdash;guide, facilitator, innovator, negotiator, catalyst, experimenter and a researcher and mdash;have been explained. Paradigm shifts in learning processes, from behaviourism to cognitivism and now to constructivism, have also been taken up. Constructivist thinking has been adopted in diverse fields like art, communication, ethnology, industrial management, law and linguistics, among many others. This has led to the generation of a large amount of research-based data bringing a greater understanding of the attributes of learners, the process of learning and the general problems associated with teaching-learning. These developments have also been explicated. The book will be useful for teachers, teacher-educators, curriculum framers, textbook authors, students and researchers in the field.