The 4-year graduation rate for Colorado students in foster care decreased substantially from the 2015-2016 school year to the 2016-2017 school year, from 33.2% to 23.6%. This study examines trends in state-level child welfare and education data to uncover possible explanations for this decline. Students in the 2017 foster care cohort tended to drop out of school earlier in high school than previous cohorts of foster youth. Because of this trend, proportionally fewer youth in the foster care cohorts participated in the state end of year academic testing and, as such, proficiency levels may be misleading indicators of foster care cohort graduation rates. The results also show that school mobility decreased, but similarly, if students are not enrolled in school, then they cannot change schools. The findings of this study suggest that dropout rates, an educational indicator routinely collected at the state level, are the best available indicator of 4-year graduation rates. [This study was commissioned by the Colorado Department of Human Services.]