This thesis develops optimization models for prioritizing payloads for inclusion on satellite buses with volume, power, weight and budget constraints. The first model considers a single satellite launch for which the budget is uncertain and constellation requirements are not considered. Subsequently, we include constellation requirements and provide a more enhanced model. Both single-launch models provide a prioritized list of payloads to include on the launch before the budget is realized. The single-launch models are subsequently extended to a sequence of multiple launches in two cases, both of which incorporate an explicit dependence on the constellation composition at each launch epoch. The first case ignores future launches and solves a series of independent single-launch problems. The second case considers all launches simultaneously. The optimization models for single- and multiple-launch cases are evaluated through a computational study. It was found that, when the budget distribution is skewed, the prioritization model outperforms a greedy payload selection heuristic in the single-launch model. For the multiple-launch models, it was found that the consideration of future launches can significantly improve the objective function values.