A system and method for injecting catalyst into a fluid catalyst cracking (FCC) unit is provided. In one embodiment, a system for injecting catalyst into a FCC unit includes at least one catalyst injection apparatus for providing catalyst to a fluid catalyst cracking unit, at least one sensor adapted to provide a metric indicative of the composition of a product stream produced in the fluid catalyst cracking unit, and a controller coupled to the sensor, for controlling the additions made by the catalyst injection system in response to the metric provided by the sensor. Another embodiment of the invention comprises a method for injecting catalyst from a catalyst injection system into a FCC unit that includes the steps of dispensing catalyst for a catalyst injection system into a fluid catalytic cracking unit, sensing an output in the fluid catalytic cracking unit, and automatically adjusting the amount of catalyst dispensed in response to the at least one sensed metric.