Early mathematics skills are predictive of later achievement, but there is evidence teachers generally provide little mathematics instruction in preschool classrooms. We conducted this survey study to better understand teachers' reported beliefs about their own mathematics skills, expectations, and practices for children with and without disabilities, and the impact of these reported beliefs and practices on the perceived effectiveness of their instruction. We found teachers had less confidence in their own mathematics skills than their mathematics teaching abilities and had differing expectations for children with and without disabilities. Their beliefs about their own mathematics abilities predicted their perceived effectiveness for typically developing children only, but their beliefs about their teaching abilities predicted their perceived effectiveness for children with and without disabilities. Implications include the need to better prepare and support teachers to teach mathematics to all children and collect data from varied sources on teachers' practices.