In the face of state cutbacks to early-childhood programs, school districts might find themselves wondering whether to invest their own scarce funds in preschool or in full-day kindergarten. A study out today has a clear message: If you want to maximize the chances of strong 3rd grade reading results, preschool programs in combination with full-day kindergarten is the way to go. But if that's not possible, it's better to go with pre-K and half-day kindergarten than relying solely on all-day kindergarten.

The report, "Starting Out Right: Pre-K and Kindergarten," uses a federal database that followed more than 21,000 students from kindergarten through 8th grade. The students' progress was gauged by the National Center for Education Statistics with specially designed tests.

The reading tests given to the children defined five levels of achievement. Researchers from the National School Boards Association analyzed the relationships between the type of pre-K and kindergarten programs the children attended and their performance on the test. They found consistently that children who attended preschool and half-day kindergarten had substantially greater chances of doing better on the reading test than those who had attended only full-day kindergarten. The benefits were particularly strong for Hispanic and low-income students and those learning English.

For instance, at level 4 on the test, which assessed children's ability to extrapolate from what they read, those who had attended preschool and half-day kindergarten were 18 percent more likely to show proficiency in that skill than those who had attended only full-day kindergarten. That number rose to 20 percent for low-income students, 24 percent more likely for Hispanic students, and 25 percent for English-learners.

The report's author, Jim Hull, writes that his findings confirm the already-established benefits of combining preschool and kindergarten. While he suggests that they could help district policymakers decide how to invest their resources, he cautions against cutting back full-day kindergarten to half-day. "The emphasis," he writes in the report, "should be on adding prekindergarten to existing kindergarten programs."