In this paper, constructivism is placed in perspective, through a presentation of its various aspects and concerns, with the aim of providing a general insight into it. The discussion focuses to show that constructivism, at its extreme, is not tenable in science education and that the version of it that is practised by educators in schools is akin to interactive learning. First constructivism's claims on knowledge are presented and their viability discussed in order to provide an introduction to the tenets upon which it is based. The psychological foundations of constructivism are then presented. Constructivism is linked to the various learning theories which inform it. It is shown that these same learning theories also provide the background for interactive learning, which is the notion of constructivism adopted by practising teachers. A discussion on science and its tenets follows, since an understanding of science and science education is useful prior to comparisons with constructivism. Science and science education are distinguished and the extent to which a constructivist philosophy fits each is discussed. The discussion then leads to the pedagogical influences and limitations of constructivism. The paper concludes with a discussion of how constructivism, as practised in the science classroom, has helped to advocate change in the science classroom and the extent to which this is viable.