There are some pitfalls to case study analysis, including lack of simplicity or narrow and idiosyncratic theories (Eisenhardt, 1989). A primary disadvantage of the case research approach is the difficulty in drawing deterministic inferences, and there are limitations in terms of the external validity of the study. These limitations are often addressed by using large samples, or using ‘before’ and ‘after’ quasi-experimental designs (Cook and Campbell, 1979). However, due to the lack of theory building in the area of environmental management systems such as ISO 14001, it is important to use the case study approach to identify differences among adopters. While causality can never be shown in case studies, analysis of data collected from multiple sites can help support the generalizability of results.