Drive systems for a drug delivery device are provided. The drive systems can be positioned within a container that stores a liquid drug to be delivered to a user. The drive systems can be coupled to a plunger positioned within the container. The drive systems can be incrementally advanced to drive the plunger further into the container, thereby expelling a portion of the stored liquid drug from the container for delivery to the user. The container can be any type of container including a pre-filled, standardized drug cartridge. The drive systems and container can be components of a wearable drug delivery device.