The purpose of this study is to analyze Abraham William Hajjar's single-family houses in State College, PA, using shape grammar as a computational design methodology. Hajjar was a member of the architecture faculty at the Pennsylvania State College (now The Pennsylvania State University), a practitioner in State College, and an influential figure in the history of architecture in the area. In this study, shape grammars are used specifically to verify and describe influences of modern architecture, as defined by Hitchcock and Johnson (1932), and influences of local traditional American architecture on Hajjar's domestic architecture. The underlying hypothesis is that Hajjar's work is the result of a hybridity phenomenon that can be traced through a computational design methodology. The first step in this endeavor and the study focus is to establish Hajjar's single-family architectural language. Future work will be concerned with verifying and describing the hybridity between modern architecture and traditional architecture expressed in Hajjar's work by comparing his grammar with grammars underlying modern and traditional architecture likewise.