Biotic stress for maize in Kenya varies in prominence depending on the variety grown and the agro-ecological zone. Major causes of stress include Striga, northern leaf blight caused by Exserohilum turcicum, maize streak virus transmitted by leafhoppers, rust (Puccinia sorghi), gray leaf spot (Cercospora zeae-maydis), stalk and ear rot (Diplodia maydis and Fusarium spp.), stalk borer, and storage pests such as weevils and large grain borers. The most effective and economic means of controlling these causes of stress is resistance breeding. The approach used to identify desirable germplasm involves exchange of germplasm among centres of the Kenya Agricultural Research Institute (KARI) and the International Maize and Wheat Improvement Center (CIMMYT). Inbred lines are screened at KARI-Muguga for maize streak and KARI-Kakamega for gray leaf spot and northern leaf blight. The selected lines based on independent culling selection are used to develop single crosses, three-way crosses, top crosses and double-cross hybrids. These crosses are evaluated through the maize testing system in Muguga and in 5 or 6 sites in western Kenya, depending on the stage of testing. Data taken during variety evaluation include relevant disease scores, ear height, maturity and grain yield. The paper presents data on selected inbred lines, single crosses, three-way crosses, top crosses and double crosses and seed production attempts for the products of the coordinated ecosystem breeding for maize in western Kenya. The approach has released two hybrids, KH633A, and KH634A, which are undergoing seed production. Two other hybrids, KM048 and KM2023, are in the final stages of evaluation, and KM048 is likely to be released. Three new hybrids, KM20077, KM20084 and KM20090, have been identified as high yielding and resistant to gray leaf spot, northern leaf blight and maize streak virus. Grain yields are 9.3 t ha–1 for KM20077, 9.7 t ha–1 for KM20084 and 10.7 t ha–1 for KM20090 compared with the checks: KN633A (7.2 t ha–1), KN634A (7.7 t ha–1) and Pb3253 (5.2 t ha–1). Twenty inbred lines resistant to northern leaf blight, gray leaf spot and maize streak virus have also been identified and are available for any of the KARI breeders to include in their breeding program. The divergent-convergent breeding approach has enabled the KARI maize-breeding program to identify desirable inbreds and hybrids in shorter time than it could have taken if individual KARI centres had been working independently. The approach has also encouraged sharing of information and germplasm among KARI maize breeders.