Manufacturing and service firms use capacity planning to match capacity with demand. It is usually subject to stochastic and time-dependent variability in demand and capacity. This dissertation investigates how to set capacity in stochastic and time-dependent operations systems and analyzes the benefit of incorporating future demand changes in the decision making. The book contains the following three scientific essays that constitute the dissertation of Jannik Vogel. [1] Quality-speed trade-offs in dynamic service systems: Do future demand changes matter? [2] Planning capacity in stochastic MTO production systems with time-dependent demand: The clear the queue effect [3] The optimal time to adapt the processing rate in a make-to-order production system