Pacific geoduck (Panopea generosa) clams are found along the Northeast Pacific coast where they are significant components of coastal and estuarine ecosystems and the basis of a highly profitable aquaculture industry. The Pacific coastline, however, is also the sight of rapidly changing ocean habitat, including significant reductions in pH. To better understand the physiological impact of ocean acidification on geoduck clams, we characterized for the first time the proteomic profile of this bivalve during early larval development and compared it to that of larvae exposed to low pH.Geoduck larvae wer reared at pH 7.5 (ambient) or 7.1 in a commercial shellfish hatchery from day 6 to 19 post-fertilization , and sampled at six time points for an in-depth proteomics analysis using high-resolution data dependent analysis. We found that larvae reared at low pH were smaller than those reared at ambient pH, especially in the prodissoconch II phase of development, and displayed a delay in their competency for settlement. Proteomic profiles revealed that metabolic, cell cycle, and protein turnover pathways differed between the two pH, suggesting that differing phenotypic outcomes between pH 7.5 and 7.1 are likely due to environmental disruptions to the timing of molecular physiological events. In summary, ocean acidification likely caused an energetic stress on geoduck larvae, casuing a shift in physiological prioritization.