In 2012, citizens of the City of San Antonio took a bold step by voting to expand access to high quality prekindergarten by dedicating a one-eighth cent sale tax to the creation of four high quality prekindergarten lab schools, a system of professional development for early education instructors, and a grant program to support high-quality prekindergarten at area school districts. This report presents the first impact study of this city initiative— Pre-K 4 SA. This study analyzed Pre-K 4 SA’s effect on pre-kindergarten enrollment in Bexar County following its authorizing election and its direct effect on the early education outcomes of students who participated in its lab schools. This study also investigated if the program produced more pronounced effect sizes on particular subgroups of students. It also examined Pre-K 4 SA’s impact relative to public pre-k. (author abstract)