A mathematical modeling framework for the simultaneous batching and scheduling of multiproduct batch plants is proposed in this work. The scheduling decisions are formulated according to campaign-based operation mode. When a stable context can be assumed on the time horizon taken into account, this operation mode assures a more efficient production management. In addition, sequence-dependent changeover times and different unit sizes for parallel units in each stage are considered. Given the plant configuration and unit sizes, the total amount of each product to be produced and the product recipes, the proposed approach determines the number of batches that compose the production campaign and their sizes, the batches assignment to units, the sequencing of batches in each unit for each stage, and the timing of batches in each unit in order to minimize the campaign cycle time. A solution strategy is proposed to enhance the computational performance of the simultaneous optimization. The approach capabilities are shown through three numerical examples.