A dual drive signature stacker having side-by-side stacker sections, each of substantially identical design and including a stepper motor for driving a pair of buckets for receiving signatures secured at spaced intervals along a drive chain driven by the stepper motor. The buckets have intercept blades supported by brackets joined to the drive chain to position one of the intercept blades of each drive assembly in front of the adjacent drive assembly so that all of the buckets of the dual drive assembly are in alignment with one another and with the signature stream. The side-by-side arrangement greatly simplifies the design cost and assembly. A microprocessor-based control system permits stacking of stacks having as few as two signatures and is further capable of forming successive signature stacks of differing count in a precision manner and compatible with the speeds of any signature flow rate.