Theories provide a framework on which researches are built. They support and strengthen research and provide a basis of support on the topical issues studied. In this paper, electronic resources and digital library are discussed pointing out some of the resources that are needed for effective functioning of the digital library. The paper considered connectivity theory, self-efficacy theory, Wormell model, Technology Acceptance Model (TAM) and Theory of Reasoned Action (TRA) in terms of the propounder of the theory, year it was propounded and statement of the theory as well as their application to electronic resources and digital library environment. The paper suggests that, prospective researchers exploring the area of electronic resources and digital libraries can make use of these and other related theories to enrich their researches.