A generalized frequency domain substructure synthesis methodology with special application to experimentally derived data is presented. This methodology affords efficient syntheses of total structure dynamics from those of its substructures. The implementing algorithms are inherently well‐suited for combining finite element characteristics of structures with those experimentally derived. The connection pattern between substructures can be quite general and of relatively complicated nature; an application of graph theory is used to perform the synthesis procedure. The methodology is based on an implicit statement of the force and displacement continuity between substructures. The use of “connecting elements” (springs, dampers etc.) between the substructures is provided for, and either simultaneous or sequential synthesis can be used. The methodology permits substructures (representing components such as gearboxes and transmissions) to be coupled by consideration of interface characteristics only. The methodology is thus ideally suited to the analysis of helicopter airframe vibration. Examples are given demonstrating the key features of the theory.