John Maurice Clark (1884–1963) was an American economist whose work combined the rigor of traditional economic analysis with an "institutionalist" attitude.

Father and son worked jointly on rewriting and expanding John Bates Clark's 1912 book The Control of Trusts, with the new edition seeing publication in 1914.

[1] The work illustrated the critical importance of accurate cost information for those seeking the effective regulation of monopolistic or oligopolistic firms.

[1] Clark argued that accounting provided an essential mechanism for the monitoring of the behavior of economically mighty firms to assure their operation within the limits established by regulation.

[1] In his 1931 book The Costs of the World War to the American People, Clark first broached the concept of the economic multiplier, the idea that "all expenditures give rise to subsequent income effects and that their aggregated sum can always be expressed as a multiple of the original disbursement.

[9] With America mired in the Great Depression and book sales weak, Clark was unable to find a commercial or academic publisher for this work.