A security gate including an outer gate and an inner gate for selective passage of people and/or pets therethrough. In one example, the security gate includes: an outer frame; an outer gate at least partially disposed within the outer frame; an inner gate disposed within the outer gate, the inner gate comprising an inner frame having at least one recess; a door at least partially disposed within the inner frame; and at least one projection extending from the outer gate and engaging the at least one recess for supporting the inner gate within the outer gate.