The current practice in multiagent systems (MAS) typically associates the environment with resources that are external to agents and their communication infrastructure. Advanced uses of the environment include infrastructures for indirect coordination, such as digital pheromones, or support for governed interaction in electronic institutions. Yet, in general, the notion of environment is not well defined. Functionalities of the environment are often dealt with implicitly or in an ad hoc manner. This is not only poor engineering practice, it also hinders engineers to exploit the full potential of the environment in MAS. We put forward the environment as an explicit part of MAS. We give a definition stating that the environment in a MAS is a first-class abstraction with dual roles: (1) the environment provides the surrounding conditions for agents to exist, and (2) the environment provides an exploitable design abstraction for building MAS applications. Considering the environment as a first-class abstraction in MAS opens up new horizons for research and development in MAS.