Using the What Works Clearinghouse

The What Works Clearinghouse (WWC) reviews education research, applies published evidence standards, and summarizes findings to support more informed educational decisions.

What the WWC is

The WWC is an initiative of the U.S. Department of Education’s Institute of Education Sciences (IES). Its resources help educators, leaders, policymakers, researchers, and families examine the quality and findings of education studies.

A critical distinction

The WWC does not endorse programs, products, practices, or policies. It reviews available research against established standards. A study’s methodological rating and its findings are separate questions: a well-designed study can report positive, negative, mixed, uncertain, or statistically nonsignificant effects.

What the WWC provides

Reviews of individual studies

Explain whether a study’s design and analysis meet WWC standards while summarizing its participants, setting, outcomes, and findings.

Intervention reports

Synthesize eligible findings from the highest-quality available research on a particular program, product, practice, or policy.

Educator’s practice guides

Present actionable recommendations developed from systematic research reviews, practitioner experience, and the judgment of expert panels.

Review data and research resources

Include searchable study records, downloadable findings, review protocols, handbooks, training, reviewer materials, and reporting guidance for study authors.

How the review process works

Define the review. Establish the topic, populations, interventions, outcomes, eligible designs, and other criteria in a protocol.
Identify eligible research. Locate studies and screen them against the protocol.
Apply evidence standards. Trained reviewers evaluate each eligible study’s design, execution, and analysis.
Review eligible findings. Examine the direction, size, and statistical significance of effects in studies meeting standards.
Summarize the evidence. Report results through study reviews, intervention reports, practice guides, data tools, or other products.

Current standards

The current WWC Procedures and Standards Handbook is Version 5.0, issued in August 2022 and revised in December 2022. Standards have changed over time, so always identify the handbook and protocol used for a particular review.

Three separate questions to ask

1. Is the study trustworthy?

Review the applicable WWC study rating and any reservations or limitations.

2. What did it find?

Examine effect direction, magnitude, statistical significance, outcomes, and consistency.

3. Does it fit here?

Compare the population, setting, implementation, resources, and outcomes with local needs.

How to interpret WWC evidence

Start with the study rating. Determine whether the study meets standards without reservations, meets standards with reservations, or does not meet standards.
Then examine the findings. Meeting standards does not mean an intervention produced a positive effect.
Inspect the evidence base. Note the studies, participants, schools, settings, and eligible outcomes behind a conclusion.
Check each outcome. Results may differ across achievement, behavior, attendance, progression, and other domains.
Consider local fit. Compare grade span, student population, setting, staffing, schedule, training, and resources.
Confirm the edition. Research may address one version or implementation—not every product with the same name.
Do not confuse “no evidence” with “evidence of no effect.” A lack of qualifying studies does not establish that an intervention is ineffective.

WWC ratings and ESSA evidence tiers

WWC study ratings address whether research meets methodological standards. The evidence tiers in the Every Student Succeeds Act (ESSA) classify the level of evidence supporting an activity, strategy, or intervention. The concepts are related—but they are not interchangeable.

Concept	Primary question	Important reminder
WWC study rating	Does the study meet the applicable methodological standards?	A strong design can produce positive, negative, mixed, or uncertain findings.
ESSA evidence tier	What level of evidence supports the proposed activity, strategy, or intervention?	Tier requirements include more than a study label; sample size, findings, setting, and population relevance can matter.
Practice-guide evidence level	How strong is the body of evidence supporting a particular recommendation?	Practice-guide levels describe recommendations and should not be casually equated with every other evidence classification.

For ESSA decisions, use the WWC’s current ESSA evidence-tier resources and verify any additional federal, state, grant, or local requirements.

A practical search strategy

Define the student group, grade span, outcome, setting, and problem.
Use Find What Works to search and filter available evidence.
Open the full intervention report or study review rather than relying on a summary label.
Compare the reviewed population and implementation conditions with the local context.
Investigate cost, training, technology, staffing, scheduling, accessibility, and implementation support using additional reliable sources.
Plan how implementation quality and student outcomes will be monitored locally.

Use evidence with professional judgment

WWC findings are an important input—not an automatic purchasing or adoption decision. Consider research quality, effect size, consistency, relevance, feasibility, equity, accessibility, cost, and local implementation capacity together.

Questions for an adoption team

Which student outcomes improved—and which did not?
How many qualifying studies, participants, schools, and settings support the finding?
How similar are the research participants and conditions to our own?
Which program version and implementation model were studied?
What training, staffing, time, technology, and ongoing support are required?
What accessibility, language, cultural, and equity considerations apply?
How will we know whether implementation is occurring as intended?
What local evidence will determine whether to continue, adjust, or discontinue the approach?

Key WWC resources

WWC resources, standards, reports, and URLs may change. Confirm the applicable handbook, protocol, report date, and study context before using WWC evidence. Reviewed August 2, 2026.