Review teams tested the systematic review procedures and principles developed under the Campbell Collaboration. Fourteen review teams selected topics for intervention reviews in social policy, education, and criminal justice. Review protocols gave criteria for the extensive research literature search. Randomised Controlled Trials were selected. Systematic reviewers should give careful attention to defining the review topic, setting study inclusion and exclusion criteria, handling variability in outcome measurement and study reporting, appropriate uses of statistical meta-analysis, and reporting review results. Significant differences in review results were observed based on review criteria and procedures.