The state's high school graduation rate has declined to 74.1 percent from 80.1 percent, but state officials pointed out they were using a new formula.
The education department previously had counted students who left schools to get General Education Development certificates as graduates.
The new standard, required under legislation passed in 2005, excludes them, as recommended by the National Governors Council.
Evan Dreyer, spokesman for Governor Bill Ritter, says regardless of the formula being used the numbers are not satisfactory.
He noted the government wants to cut the drop out rate in half within a decade.
Females outperformed males with a graduation rate of 78 percent compared to 70.3 percent.
The rate for American Indian students was 56.9 percent; for Asian students, 82.5 percent; for black students, 62.7 percent; for Hispanic students, 56.7 percent; and for white students, 80.8 percent.