The production of the Pacific oyster, Crassostrea gigas, is an established industry along the west coast of the USA. Historically produced for shucked meat markets, there is a growing shift towards hatchery-produced single-seed culture of Pacific oysters for the live or half-shell market. Here we describe the development of a commercial-scale family breeding program for C. gigas in the US Pacific northwest. A starting point was to understand the nature of the genetic variation for this population and determine how that influences the variation in commercial traits and genetic variation was clearly explained by the additive genetic model. As part of this process, genetic parameters (heritabilities and genetic correlations) were calculated for key productivity and consumer traits. The traits under investigation were total weight, meat yield, shell shape (height and width index), hook angle and general field survivability. Between 2017 and 2021 the program successfully produced 424 full-sib families across 5 annual spawning cycles using a 2x2 mating design. Full-sib families were deployed to 12 separate field trials across 3 different sites within the Puget Sound (Bay Center, Olyview and Discovery Bay) to evaluate performance and survival. Heritabilities were calculated from variance components estimated using a mixed animal model and were as follows - Total weight: h2 = 0.31 ± 0.04; Width Index: h2 = 0.43 ± 0.04; Meat yield: h2 = 0.33 ± 0.04; Hook angle: h2 = 0.45 ± 0.05; Height index: h2 = 0.42 ± 0.04; and Survival: h2 = 0.15 ± 0.02 (underlying scale). All traits show scope for improvement through selection, however, genetic correlations (rg) amongst traits ranged from moderately negative to moderately positive, indicating the importance of developing an appropriately weighted selection index in the future. For a given trait, rg between sites was generally highly positive, indicating limited genotype by environment interaction across the trial environments. We highlight the importance of accounting for the origin of breeding program founders (i.e. genetic group) when estimating genetic parameters and breeding values (EBV), and demonstrate the presence of baseline genetic differences amongst founder broodstock groups, and present data showing the gains made relative to these founders.