In this thesis, two mathematical models were developed and applied to optimize demand-responsive transit systems using zonal strategies. Demand-responsive transit systems provide services between a residential area and a terminal. The first model considers a scenario where the terminal is located outside the service area, which optimizes the area of zones and bus capacity by minimizing the costs occurring within the entire service area; while the second model designs the transit system with its terminal sitting within the service area by minimizing the costs generated in service zones separately. Case studies for the application of both models were conducted for a presumptive demand-responsive transit system operating in northwest Calgary, showing that the models can successfully assist in designing demand-responsive transit systems. Furthermore, sensitivity analysis was conducted to identify the sensitivity of the model output to each model parameter.