Purpose: The purpose of this paper is to investigate the change in management accounting and control systems (MACSs) within two large public manufacturing companies in Libya so-called Trucks and Buses Company (TBC) and National Trailers Company (NTC). Design/methodology/approach: The paper is based on semi-structured interviews, an analysis of documents and observations. It draws on New Institutional Sociology (NIS) perspective (DiMaggio and Powell’s 1983) as theoretical framework to provide explanations regarding how the MACS in the two companies were shaped by various factors. Findings: The main factors identified in shaping the operations of the MACS were the need to comply with the political pressures, the Libyan Government’s laws and regulations, the instructions imposed by the management committee in both companies, leading organizations’ pressures (ISO), customer satisfaction (coercive isomorphism), the influence of professional associations (normative isomorphism) and the need to imitate efficient organizations in order to be more legitimate and successful (mimetic isomorphism). Research limitations/implications: The findings of the study have implications for understanding the operations of MACS in developing countries. Future research could focus on alternative theoretical perspectives for the investigation of the process of change in MACS such as structuration theory, agency theory and actor-network theory. Originality/value: The proposed theoretical framework provides insights into the process of change by focusing on the interplay between the institutional forces, market forces and intra – organizational power relationships to overcome the criticism of NIS that it downplays the role of market forces and intra – organizational power relations.