Given the progressively increasingly level of government and public environmental awareness, environmental management has emerged as a key component in the overall management of hydrocarbon exploration, development, and production. This paper examines how Lasmo Oil (Malacca Strait) Ltd. (LOMSL) has set up and implemented its environmental management system to comply with Indonesian regulatory requirements and to understand and deal with environmental and community issues proactively in its areas of operation. Initiated in 1989, the current achievements of the LOMSL are described. The results show that by setting up an environmental management system and positively implementing a comprehensive environmental management program, LOMSL has managed to solve its major environmental problems. We found that to establish and to maintain a satisfactory level of environmental performance, broad-ranging consideration must be given to aspects of a regulatory and institutional, socioeconomic, and ecological nature. Management commitment and participation is also identified as essential if a sustained level of high-quality environmental management is to be achieved.