The proximity of coral reefs to coastal urban areas and shipping lanes predisposes corals to petroleum pollution from multiple sources. Previous research has evaluated petroleum toxicity to coral using a variety of methodologies, including monitoring effects of acute and chronic spills, in situ exposures, and ex situ exposures with both adult and larval stage corals. Variability in toxicant, bioassay conditions, species and other methodological disparities among studies prevents comprehensive conclusions regarding the toxicity of hydrocarbons to corals. This research evaluated the 48-hour toxicity of 1-methylnaphthalene to Porites divaricata using a continuous-flow passive dosing system. The range-finding exposure evaluated the dosing protocol and verified the effectiveness of the passive dosing technique at maintaining exposure concentrations. The full-toxicity exposures resulted in a precise estimate of toxic threshold concentrations for use in the target lipid model. The target lipid model promoted comparisons across different species by calculating the critical target lipid body burden of 355.7 µmol/ g lipid for P. divaricata. This indicates a greater resilience to petroleum hydrocarbon exposure compared to other species for which these data are available.