Rising sea surface temperatures pose the greatest threat to corals and lead to bleaching. Coral bleaching predictions typically consider duration and magnitude of elevated temperatures relative to a locally defined thermal threshold. However, recent work suggests that heterogeneity in bleaching patterns may be better explained by degree of diel thermal variation (DTV). We sourced colonies of the reef-building coral Siderastrea siderea from six reefs across Bocas del Toro, Panama which ranged in mean DTV (~1-3°C). We conducted a 50-day common garden experiment to assess the influence of low, moderate, and high DTV (2, 3, and 4°C, respectively) and then performed a two-week thermal challenge (32°C) followed by a two-week recovery period. Metrics of coral host (growth, carbohydrate, protein, tissue thickness, corallite area) and symbiont (carbohydrate, chlorophyll, density, and mitotic index) physiology were assessed to disentangle how natal reef DTV modulates a coral’s response to DTV, thermal stress, and recovery. Results suggest that corals sourced from higher DTV sites outperformed corals from less variable sites, regardless of treatment. High experimental DTV increased growth and corals that experienced moderate DTV maintained higher symbiont densities after recovery. Analyses are ongoing; however, results will shed light on how DTV modulates a coral’s response to temperature stress and recovery. Our data support the hypothesis that DTV in situ and in husbandry plays a central role in growth and symbiosis of reef-building corals, highlighting the need to consider DTV when evaluating the resilience of corals to global change.