This paper examines the existing environmental management communications practice among project participants in project development processes. There is a growing pressure for all project participants to extend their traditional business objectives of only lowering cost and shortening project duration to improve environmental performance. In achieving better environmental performance, it is essential to collect responses from project participants including project clients, consultants, contractors and various sub-contractors to build up collaboration. As this collaboration is based largely on communications among various parties, the validity and effectiveness of the communications are essential to enable effective collaboration. By investigating practical applications, this paper identifies gaps of communications among project participants, and shows that these gaps present barriers to the improvement of environmental performance in construction. Possible solutions to communication gaps are investigated, leading to the proposal of a communicationmapping model for environmental management (CMEM). The CMEM is proposed as a method aimed at effectively implementing environmental management in construction practice. Data used for this study are collected from six construction projects in Hong Kong. A free-flow mapping approach is also employed to assist the investigations. It is believed that this study can help improving communications among project participants and environmental performance in the construction industry.