On 29 April 1963, the poet and performer Jackson Mac Low mailed a series of postcards to a number of his artistic colleagues. Each postcard contained the title and text of a composition by Mac Low. Taken as a series, these works probe the limits of the still-emerging format of the event score. Some compositions ask performers to complete virtually impossible tasks; others appear effortlessly simple. The three Social Project scores, in particular, seem designed to spur their recipients to think more clearly, in both conceptual and practical terms, about the theories of social change that were being implicitly invoked in this newly expanded mode of artistic performance.