This study found that government-funded surgical sterilization of companion animals has been widely promoted as a means of decreasing shelter intake and euthanasia. However, little information is available about the true impact of these programs on community and shelter nonhuman animal population dynamics. This study estimated the impact of the Animal Population Control Program in New Hampshire by comparing shelter intake and euthanasia data before and after the onset of the neutering initiative. Regression analysis demonstrated a significant decrease in cat intake and euthanasia during the years after program onset, a trend that appears to begin prior to the program's initiation; however, there was no decrease in dog intake or euthanasia. This study also estimated the impact of the Austin-based EmanciPET FreeSpay/Neuter Program by comparing shelter intake and euthanasia data from the targetedprogram areas versus nonprogram areas within the city. Regression analysis demonstrated a significantly lower rate of increase for dog and cat intake and euthanasia in the program areas. Prospective studies should determine the effectiveness and affordability of different models for funding and delivering neutering services.