Most of a product’s life-cycle characteristics are determined during the configuration design stage, when the product’s components are selected and arranged spatially and logically. One set of choices that determines many life-cycle characteristics is fastener type selection. In this paper, an assembly modeling representation is presented that supports changes in fastener types and fastening mechanisms while maintaining consistent degrees-of-freedom among fastened components. A fastening mechanism template and a corresponding instantiation algorithm have been developed for tensile-compressive fasteners. The template consists of four main elements: an assembly representation template, CSG tree fragments (to allow geometry construction), geometric constraint templates, and a parametric relationship template to integrate analysis equations into fastener models. Each particular fastener type is modeled by a specific template that is developed manually using the general template as a guide. The instantiation algorithm maps a particular fastening template onto an existing assembly model (assemblies, components, geometry, and mating relationships) in order to add fasteners to a product. A similar fastener substitution algorithm enables the replacement of one fastener type with another. The use of the algorithms is illustrated in the configuration design of an automotive center console. The paper concludes with a brief demonstration of how fastener selection affects life-cycle product characteristics.