TheBonnMuresource is a transposon-tagged mutant collection designed for functional genomics studies in maize. To expand this resource, we crossed an activeMutator(Mu) line with dent (B73, Co125) and flint (DK105, EP1 and F7) germplasm, resulting in the generation of 8,064 mutagenizedBonnMuF2-families. Sequencing of theseMu-tagged families revealed 425,924 heritableMuinsertions affecting 36,612 (83%) of the 44,303 high-confidence gene models of maize (B73v5). On average, we observed 12Muinsertions per gene (425,924 total insertions/ 36,612 affected genes) and 53 insertions perBonnMuF2-family (425,924 total insertions/ 8,064 families).Muinsertions and photos of seedling phenotypes from segregatingBonnMuF2-families can be accessed through the Maize Genetics and Genomics Database (MaizeGDB). Downstream examination via the automated Mutant-seq Workflow Utility (MuWU) identified 94% of the germinal insertion sites in genic regions and only a small fraction of 6% inserting in non-coding intergenic sequences of the genome. Consistently,Muinsertions aligned with gene-dense chromosomal arms. In total, 42% of allBonnMuinsertions were located in the 5′ untranslated region (UTR) of genes, corresponding to accessible chromatin. Furthermore, for 38% of the insertions (163,843 of 425,924 total insertions)Mu1,Mu8andMuDRwere confirmed to be the causalMuelements. Our publicly accessible EuropeanBonnMuresource has archived insertions covering two major germplasm groups, thus facilitating both forward and reverse genetics studies.