A Multisite Randomized Controlled Trial of Descubriendo la Lectura (DLL)

There is a pressing need for Spanish-language early intervention programs for students at risk of literacy failure. One such program is the Spanish-language reconstruction of Reading Recovery known as Descubriendo la Lectura (DLL).

DLL offers one-on-one lessons in Spanish for a period of 12‒20 weeks to first-grade Spanish-speaking English learners (ELs) struggling with reading and writing. The program extends the successful Reading Recovery approach to ELs by first addressing literacy in their native language. Lesson activities include reading familiar books, reading a recently assigned book while teachers take a running record, working with letters or words using magnetic letters, writing a story, assembling the child’s cut-up story, and reading a new, strategically selected book. Promising findings from a previous experimental study of DLL suggest a need to study whether results can be replicated for a wider sample.

The current study is a multisite student-level randomized controlled trial (RCT) involving three cohorts of students (2016‒17, 2017‒18, and 2018‒19). Students were randomly assigned to an immediate treatment group or a delayed treatment group, with the latter serving as a control group for the former.


Though the average impact of d = .14 for the four English literacy measures was relatively modest, it will be important to continue investigating longitudinal English-language outcomes in second and third grade, and the extent to which these strong initial treatment effects in Spanish transfer to later outcomes.

Results suggest that DLL produces a clear benefit to students across many dimensions of literacy, and those impacts are consistent across schools and years. Comparing the mean effect size of d = .6 found across the 11 Spanish literacy measures to benchmarks provided by Hill, Bloom, Black, and Lipsey (2008), the average DLL impact is equal to 60% of the overall literacy growth that occurs during the first-grade year. Indeed, as a supplemental intervention spanning only 12‒20 weeks, DLL produces impressive impacts of a magnitude rarely seen for educational programs of any type.

Managing Researcher
Bo Zhang
Senior Researcher