Canola (Brassica napus L.) is a major temperate crop in Australia, and there is a dynamic commercial breeding industry producing new cultivars for growers. Improved stress tolerance in canola cultivars is of increasing importance, but it is difficult to detect and to breed for. Public-sector researchers need reliable information on which existing cultivars possess good stress tolerance and can be used as germplasm sources for traits worthy of pre-breeding research. We utilized the Australian National Variety Trial (NVT) data for released canola cultivars to examine two aspects of canola performance. First, the stress tolerance of cultivars was examined using low-yielding vs. high-yielding environments. Second, the genotype × environment interactions of cultivars were investigated and whether or not they exhibited significant crossover interaction, indicating general or specific adaptation. The NVT dataset consisted of results for 144 cultivars tested over 7 yr (2008¿2014) at 101 locations and in 782 field plot experiments. Large differences in stress tolerance were seen in the data, and certain cultivars are recommended as candidates for further investigation. Many cultivars showed genotype × environment crossover interactions, indicating specific rather than general adaptation, although a few exceptional cultivars were high yielding and stable.