The Healthy Hunger-Free Kids Act (HHFKA), which took effect at the beginning of the 2012-2013 school year, updated the meal patterns and nutrition standards for the National School Lunch Program (NSLP) and the School Breakfast Program (SBP) to align with the 2010 Dietary Guidelines for Americans. This study assessed changes in energy and nutrient density of 1.7 million school meals and meal participation rates before and after implementation of the HHFKA. Researchers analyzed foods selected by 7,200 middle and high school students in a diverse urban school district in Washington state from January 2011 to January 2014, which spans 16 months before and 15 months after implementation of the updated standards. The nutritional quality of the foods students chose was calculated by assessing the amount of calcium, vitamin C, vitamin A, iron, fiber, and protein in each item; and the calorie content of the foods served was assessed by calculating the energy density (amount of calories per gram) of each food item. Researchers found that the nutritional quality of meals selected by students significantly improved following the new meal standards, and the new standards had no effect on school lunch participation.