We present an alalysis of the collection of alpha-particle generated charge by collectors surrounded by either uniform reflecting or uniform absorbing surfaces. These are the two extreme cases of any real condition that exists in IC's. The analysis of the upper limit of charge collection should be more useful for circuit design than the previously available lower limit. It is assumed that the charge transport is by diffusion. The effects of collector size, α-particle energy, and the separation between the collector and the alpha track are studied. When the α-particle strike is through the center of the collector, the difference in collected charge for the two cases is up to a factor of two. When the α-particle strike does not pass through the collector, the difference is much greater. The collected charge scales approximately linearly with the collector side length.