We propose cumulative meta-analysis as the procedure of completing a new meta-analysis at each successive wave in a research database. Two facets of cumulative knowledge are considered: the first, sufficiency, refers to whether the meta-analytic database adequately demonstrates that a public health intervention works. The second, stability, refers to the shifts over time in the accruing evidence about whether a public health intervention works. We used a hypothetical data set to develop the indicators of sufficiency and stability, and then applied them to existing, published datasets. Our discussion centers on the implications of the use of this procedure in evaluating public health interventions.