This paper explores the relationship between the implementation of an environmental management system (EMS) and environmental performance (EP) from a management accounting and control (MAC) stance. Particularly, it asks: How is environmental performance constructed in firm's using ISO 14001? And, b), what is the relationship between ISO 14001 and environmental performance? Grounded in the relative novelty of a qualitative cross-case approach to construct EP from the perspectives of the SMEs as an understudied empirical context in MAC research, it finds that EP is a fluid, multidimensional concept that embraces not only environmental, but also social, operational and financial dimensions. It also regards the interrelation of processes and outcomes, as well as field and firm, within temporal and spatial horizons. The findings of this research contribute to the MAC literature by proposing that ISO 14001 results in the formalisation of performance measures and outcomes in SMEs. Nevertheless, it presents EP as a multidimensional construct. Therefore, there are research limitations in trying to capture it solely as an output at the intra-organisational level in MAC studies through quantitative items. Consequently, future theorisations of the environmental management control system require a recognition of the intra-organisational and extra-organisational dimensions that contribute to the construction of EP for SMEs. For SMEs, this study highlights the value of EMS in improving both substantive and symbolic performance.