This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance levels--basic and above, proficient and above, and advanced; (2) Background information about limitations of the state's test data and characteristics of the state's testing system, including major changes in its testing system; (3) Figures and tables with the percentages of students scoring at the proficient level and above for all years with comparable data since 1999 and for all grades tested under the No Child Left Behind Act; (4) Figures and tables with percentages of students performing at three achievement levels--basic, proficient, and advanced--for all years with comparable data and for grades 4, 8, and 10 (or adjacent grades, in the case of states that lack comparable trend data for these default grades); (5) Figures and tables with mean scale scores, standard deviations, and effect sizes for all years with comparable data and for the three grades analyzed in this study; and (6) Figures and tables with mean scale scores, standard deviations, and effect sizes for all years with comparable data and for the three grades analyzed in this study. Oklahoma has made a number of changes to its testing program in recent years. As a result, trend lines start in different years for the elementary level (2005) and middle school level (2002) and for high school reading (2003). Only two years of comparable data are available for high school math, too few to determine a trend. In general, Oklahoma students made gains at the basic, proficient, and advanced achievement levels at all of the grade levels analyzed, except for a decline at the advanced level in elementary reading. Specific results include: (1) In reading, the percentage of students performing at the basic level and above increased at a moderate-to-large rate at all three grade levels analyzed; in math, the percentage basic rose slightly at the elementary grade analyzed and at a moderate-to-large rate at the middle school level; (2) The percentage of students scoring at the proficient level and above in reading increased at a moderate-to-large rate at all three grade levels analyzed; in math, there was also a moderate-to-large gain in the percentage proficient at the elementary and middle school levels; and (3) The percentage of students reaching the advanced level in reading decreased at a moderate-to-large rate at the elementary grade analyzed, increased slightly at the middle school grade, and rose at a moderate-to-large rate at the high school level; in math, there was also a moderate-to-large gain in the percentage of advanced students at the elementary and middle school levels. (Contains 6 figures and 6 tables.) [For "State Test Score Trends through 2007-08, Part I: Is the Emphasis on 'Proficiency' Shortchanging Higher- and Lower-Achieving Students?," see ED506121. For "State Test Score Trends through 2007-08. Part II: Is There a Plateau Effect in Test Scores?," see ED506122.]