Crops with multiple biotechnology-derived traits (stacks) offer advantages over individual-trait products (singles) such as more mechanisms of action in herbicide tolerance or pest resistance and are increasingly important in the agricultural biotechnology industry.  Currently, global regulatory requirements are not harmonized on the types of environmental data needed to allow cultivation or import of stacks.  The demonstration of environmental safety of the singles leads to a predictably similar outcome in breeding stacks, requiring much reduced or no breeding stack environmental data submission requirements in the U.S. and Canada.  In contrast, many world areas continue to require substantial environmental safety assessments on breeding stacks (e.g., the European Union and Korea).  To date, across the many commercial breeding stack products, no meaningful observations of increased environmental risk compared to conventional counterparts have been documented.  For this reason, and as experience continues to be gained with genetically modified crops, it is proposed that environmental safety data for breeding stacks is not necessary if each single has prior regulatory approval and there is no plausible hypothesis for an interaction between the single traits that would create an environmental risk.  Empirical evidence is provided in support of this approach using a maize breeding stack of insect protected MON 89034 (YieldGard® VT PRO®) and glyphosate tolerant NK603 (Roundup Ready® 2) for which environmental safety would be predicted based on the criteria above.  Data from environmental safety studies, including agronomic and phenotypic assessments; qualitative assessments of abiotic, disease, and insect stressor damage; and quantitative assessments of non-target arthropod abundance are presented from multiple world areas for MON 89034, NK603, and the breeding stack MON 89034 × NK603.  Environmental safety conclusions for each product are compared, showing that environmental safety of MON 89034 × NK603 was adequately demonstrated by environmental safety assessments of its component singles MON 89034 and NK603.  This approach, if adopted in world areas where environmental safety assessments of breeding stacks are required, would provide a straightforward means of breeding stack approval that is common across regions, reduces unnecessary regulatory burdens, and maintains adequate safety information for regulators.