We explored coral gene expression patterns and the physiological response of their dinoflagellate symbionts (Symbiodinium) to temperature stress. Fragments of Montastraea faveolata were field-collected in the Mexican Caribbean during summer (2012) and winter (2011) seasons. For each seasonal experiment, the corals were acclimated to 28degC under controlled tank conditions. Half of the fragments were kept in the controlled 28degC conditions and half were increased to 32degC for ten days. Subsequently the treatment corals were returned to 28degC and allowed to recover for up to six weeks. The same protocol was used for two different experiments in winter and summer. After ten days of thermal stress, we observed break down of symbiosis (bleaching) in the summer experiment. The symbiosis was robust in corals collected for the winter experiment, despite exposure to equivalent stress. We analyzed host transcriptome response to temperature stress. Several cellular pathways appeared to contribute to holobiont robustness. Corals differentially express a variety of enzymes that react with reactive oxygen species produced by stressed algal symbionts. Genes with functions attributed to calcium ion regulation and cell-cell adhesion are also differentially expressed before activation of the cell death pathways that cause symbiosis breakdown. We measured clear physiological differences in resident Symbiodinium populations between winter vs. summer experiments suggesting that the regulation of dinoflagellate physiology also contributed to holobiont robustness. We will discuss the host transcriptome response, organismal performance and the evolution of holobiont tolerance to thermal stress associated with these physiological differences. We will use this case study to discuss a theoretical model of biological robustness for the coral-algal holobiont.