Best practices are conceived in management as improvement programs leading to higher organizational performance. We hereby take an interest in the effects of Enterprise Resource Planning (ERP), systems implementation as managerial tools on firm performance, in connection with the organizational processes, and accounting and controlling systems. The aim of this paper is to investigate how the mutual evolution of both organizations and systems transforms the case of ERP implementation in best practices in management and accounting in an emerging economy. This research comes in the context of a slowly developing research based on empirical data in Romania in this area. However, best practices need to be promoted in order to stimulate change, in an increasingly complex and competitive environment, and with fewer resources available to organizations. By an in-depth longitudinal case study, we illustrate how both the ERP system and the case organization evolved, triggering a fit which consequently led to improving organizational performance. The paper has practical contributions for the Romanian business environment, in that Romanian managers and IT employees might become aware how they can leverage their ERP system to exploit its fuller potential, and regarding the importance of the organizational context for the implementation and postimplementation processes.