GM maize hybrids MON-89Ø34-3 × MON-88Ø17-3, MON-89Ø34-3 × MON-ØØ6Ø3-6, and MON-ØØ6Ø3-6 and a corresponding conventional isohybrid control were planted in each of 36 studies (19 Experimental Phase, 17 Pilot Phase) in a randomized complete block design (RCBD) with three to four replications and up to four locations per ecoregion per year (Supplementary Tables 1 and 2). Twelve agronomic and phenotypic characteristics were evaluated throughout the season (Supplementary Table 3). In addition, plant response to target insect pests (i.e., stalk borer tunnel length and tunnel number, Diabrotica root damage, corn earworm damage, and Spodoptera leaf damage) were evaluated according to standard methods (Davis et al. 1992; Oleson et al. 2005). When present, cutworm (Agrotis and/or Spodoptera spp.) seedling damage was also documented (Supplementary Table 3). Weed control levels (% of total weed population eliminated) by total applications of glyphosate vs. mechanical weed control treatments were documented at multiple locations. Agronomic, phenotypic, and insect damage data collected from each individual study were subject to an analysis of variance (ANOVA). The means, standard errors, and sample sizes of the test and control hybrids for agronomic, phenotypic, and insect damage measurements from each study were generated from the statistical analyses of individual studies and included in a meta-analysis.