Actions such as the WEEE Directive and RoHS Directive are forcing electronics suppliers to transition their products from tin-lead to lead-free solder in order to support consumer goods. The defense and avionics industries obtain their parts from the same suppliers and must adapt to these new lead-free products. In this thesis, a cost model was created to evaluate the transition from lead-free to tin-lead electronics. The model provides the industry with multiple transition options and determines the costs associated with each of these options. The options modeled are an all tin-lead assembly, a lead-free assembly and a mixed assembly. The cost model assimilates all the costs involved in the transition to lead-free and includes changes in reliability, and plan development and maintenance costs. The model requires users to input information specific to their organization. The model also predicts costs incurred when more than one plan, i.e., a specific set of materials and qualifications, must be supported.