Eighteen of the county's 41 middle and elementary schools scored 90 percent proficient or better in both reading and math.
Kranefeld called the system's overall performance "a huge accomplishment."
In Howard County, which annually posts results above the state average, 94 percent of elementary school students scored proficient or advanced in reading and 92 percent did so in math. At the middle-school level, 92.6 percent of students scored proficient or advanced in reading and 87.3 percent in math.
"We're very pleased with our overall scores. We're achieving at higher levels than we've ever achieved before," said Rebecca Amani-Dove, county director of student assessment and program evaluation.
"Overall, we continue to see gains. We've also seen improvement in students receiving special education services."
Forty-nine of Howard County's 58 elementary and middle schools met AYP targets this year. Seven schools have been identified for local attention — Cradlerock School, Dunloggin, Elkridge Landing and Harper's Choice Middle, as well as Fulton, Running Brook and Swansfield elementaries. Local attention means a school needs to focus efforts on the individual needs of students in the areas in which they did not meet the target.
School officials said Mayfield Woods Middle and Wilde Lake Middle are in their first year of a school improvement program. Oakland Mills Middle, which progressed from school improvement to corrective action last year, met AYP targets in 2011. It will be removed from the school improvement category if it meets the goals next year.
Jeffers Hill and Veterans elementaries and Murray Hill Middle also made adequate progress in 2011 and are no longer identified for local attention, Amani-Dove said.
Running Brook Elementary posted the 11th-largest gain among all schools in the state in reading and math, with a total gain of 22.04 percentage points, according to data analyzed by The Baltimore Sun.