Publicly funded single-sex schooling (SSS) has proliferated in recent years and is touted as a remedy to gaps in academic attitudes and achievement, particularly for low-income students of color. Research on SSS is rife with limitations, stemming from selective admissions processes, selection effects related to socioeconomic status, a lack of ethnic diversity among students, and a neglect of boys' schools. Addressing those concerns, the current study is a quasi-experimental investigation of the academic attitudes and achievement among 11th-grade low-income students of color enrolled in nonselective, urban neighborhood public single-sex and mixed-sex high schools. Students in SSS reported significantly more negative attitudes about English/reading compared to students in mixed-sex schools (MSS), while there were no differences in math or science attitudes. Data from standardized tests indicate that SSS was associated with poorer achievement among boys in reading and math but higher achievement among girls on math, science, reading, and writing.