This study examines the effects of the extension of compulsory schooling from 5 to 8 years in Turkey—which substantially increased the grade completion rates not only during the new compulsory years but also during the high school years—on the equality of educational outcomes among various subpopulations. While longer compulsory schooling decreases the educational gap for most subgroups—in particular, the gender gap in rural areas, the ethnic gap among men in both urban and rural areas, and the ethnic gap among women in urban areas; at the same time, it increases the gender gap in urban areas as well as the ethnic gap among women in rural areas. For instance, the gap in the 8th grade completion rate between ethnic Turkish and Kurdish women in rural areas increases from 22.5 to 44.6 percentage points for the 1989 birth-cohort. These findings suggest that the differences among subpopulations in the change in schooling costs (both monetary and psychic) during the new compulsory schooling years, in the costs of non-compliance with the policy, in labor force participation, and in the drop-out behavior in earlier grades are the key underlying factors.