In this paper, we develop a conceptual model for understanding human-related information practices and their behavioural activities. Our focus is on forging new possibilities to explore and improve the contemporary dilemma when human activities fail due to the lack of the needed information, which is here understood as information inadequacy. More precisely, information inadequacy is defined as vulnerable and inadequate information, composed by the dichotomy of information lack and/or of information overflow, which imposes complexities and unexpected behaviour on human, social and industrial affairs. By exploring the lack of needed information in human, social and industrial affairs, we conducted an inquiry into different empirical situations manifesting information inadequacy, subsequently examining the various theoretical bodies that relate to information inadequacy. The key question was: Which theories may explicate the key human behavioural patterns that cause information inadequacy? To answer this question, our paper presents initial guidance with a systematic approach that focuses on evaluating and further improving research and practice in terms of information relevance. The empirical cases are largely based on major human, social and industrial dysfunctions: the Lehman Brothers' bankruptcy 2008, and the Enron bankruptcy 2001, the disasters of the Columbia space shuttle in 2003, and the Challenger in 1986. The analyses are examined through theories of information behaviour that influence communication processes where two or more different actors are required to engage in activities of communicating information. The results include the identification of four information exchange patterns: influenced, intentional, hindered, and unaware. Furthermore, we discuss the implications of the model for practice with information. The paper concludes by reviewing the role of information inadequacy in economic, social and political contexts that remain challenging.