The Massachusetts Environmental Policy Act (MEPA) requires that state agencies study the environmental consequences of their actions, including permitting and financial assistance. It also requires them to take all feasible measures to avoid, minimize, and mitigate damage to the environment .

MEPA further requires that state agencies "use all practicable means and measures to minimize damage to the environment," by studying alternatives to the proposed project, and developing enforceable mitigation commitments, which will become conditions for the project if and when they are permitted.

MEPA applies to projects that exceed MEPA review thresholds and that require a state agency action, specifically that they are either proposed by a state agency or are proposed by municipal, nonprofit or private parties and require a permit , financial assistance , or land transfer from state agencies.

MEPA review is not a permitting process. MEPA requires public study, disclosure, and development of feasible mitigation for a proposed project . It does not pass judgement on whether a project is environmentally beneficial, or whether a project can or should receive a particular permit. Those decisions are left to the permitting agencies. MEPA review occurs before permitting agencies act, to ensure that they are fully cognizant of environmental consequences of their actions.

MEPA review provides the mechanism through which this information collection and mitigation mandate is executed. MEPA empowers the Secretary of Energy & Environmental Affairs to oversee the review process. The process is public and encourages comments from citizens and from state, regional and local agencies.

The MEPA Office is the staff of the Secretary of Energy & Environmental Affairs responsible for day-to-day administration of the MEPA review process. Its job is to solicit comments from the general public and agencies; represent the Secretary at the public consultation sessions on projects; coordinate project review with the proponent, consultants, and interested agencies and citizens; and make a recommendation to the Secretary regarding the adequacy of environmental documentation submitted for a project.