This report presents results of the National Assessment of Educational Progress (NAEP) U.S. science assessment in 2011. A representative sample of 122,000 eighth-graders participated in the 2011 NAEP science assessment, which is designed to measure students' knowledge and abilities in the areas of physical science, life science, and Earth and space sciences. The average eighth-grade science score increased from 150 in 2009 to 152 in 2011. The percentages of students performing at or above the "Basic" and "Proficient" levels were higher in 2011 than in 2009. There was no significant change from 2009 to 2011 in the percentage of students at the "Advanced" level. Score gaps between White and Black students and between White and Hispanic students narrowed from 2009 to 2011. In comparison to 2009, average science scores in 2011 were 1 point higher for White students, 3 points higher for Black students, and 5 points higher for Hispanic students. There were no significant changes from 2009 to 2011 in the scores for Asian/Pacific Islander or American Indian/Alaska Native students. Average scores for both male and female students were higher in 2011 than in 2009. Male students scored 5 points higher on average than female students in 2011, which was not significantly different from the 4-point gap in 2009. The average science score for public school students was higher in 2011 than in 2009, while there was no significant change in the score for private school students. Private school students scored 12 points higher on average than public school students in 2011, which was not significantly different from the 15-point score gap in 2009. (Contains 12 figures and 2 tables.)