It became apparent that while the mental health system as a whole was overcrowded, the most urgent need was in the metropolitan area. Intense debate over possible solutions occurred in 1908-1926. The Trustees of the newly acquired Boston State Hospital advocated for expansion of thier facility to a 5,000 patient capacity, but were unable to convince the State Board of Insanity of the merits of that proposal. The need for a second metropolitan area hospital was indentified as eary as 1908.

Introduced to the state legislature in 1912, the board authorized spending in January of 1915. A site that was in close proximity to the Walter E. Fernald State School was immediately acquired. Plans were prepared for a 1,900 patient facility to be built on the cottage/colony plan. No action was taken for several years due to the Trustess of Boston State Hospital continue to argue for thier own expansion and the first World War diverted state attention and funds.

Finally, in 1927, the State legislature responded by appropriating $1,500,000 for preparation of the Waltham site. The ground breaking ceremony took place on December 27, 1927 at the Administration Building. Cornerstone laying ceremonies were held on October 17, 1928. Construction costs were kept down by the use of the plain red brick buildings of early American colonial type. Trim elements, including pedimented pavilions and quoins, were deleted from the ward buildings. As the first campus developed in the automobile age, Met State did not require immediate adjacency to railroad facilities. As the most recent of the State's institutional treatment centers for the insane Metropolitan State Hospital represented the third and final stage in the evolving form of hospitals for the mentally ill. Like it's predecessors, the Kirkbride and cottage/colony, it responded to increases in patient populations within the constraints of a publicly funded budget which both often failed.