Only about one-quarter of U.S. high school seniors showed solid performance in math on an assessment known as the nation's report card.
The 12th-graders performed better in reading -- almost 4 in 10 reached the level known as "proficient" or better.
Scores in both subjects from 2013 have remained stagnant from when the National Assessment of Educational Progress was last given to this grade in 2009.
The poor showing seems likely to reinforce concerns that a large number of high school graduates show up for college and the workplace unprepared.
Education Secretary Arne Duncan says the country must do better for all students.