Population control in dogs and cats is an important goal for many groups. Control measures over the years has included surgery, hormonal therapy and more recently immunological control. The current presentation discusses dog population control with an emphasis on immunologic control. Specifically, vaccination with purified zona pellucida (ZP) glycoproteins leads initially to immunocontraception and then to the profound and irreversible changes of immunosterilization. The preliminary studies are extremely encouraging on developing a vaccine for lasting canine population control.