In "Puerto Rico: Island of Progress" Justus Holsinger describes the political, social, and economic changes that took place in Puerto Rico between 1952 and 1969. As a member of the La Plata Mennonite Project from 1943-1945 and as director from 1948-1952, Holsinger was ideally placed to observe conditions in Puerto Rico, which he described in his 1952 book, "Serving Rural Puerto Rico." Written in 1970 after six months spent in Puerto Rico studying conditions seventeen years after his first stay there and now published for the first time, "Puerto Rico: Island of Progress" contains Holsinger's reflections on the momentous changes that took place in Puerto Rico during the Munoz Marin years."