The sustainable seafood movement is at a crossroads. Its core strategy, also known as a theory of change, is based on market-oriented initiatives such as third-party certification but does not motivate adequate levels of improved governance and environmental improvements needed in many fisheries, especially in developing countries. Price premiums for certified products are elusive, multiple forms of certification compete in a crowded marketplace and certifiers are increasingly asked to address social as well as ecological goals. This paper traces how the sustainable seafood movement has evolved over time to address new challenges while success remains limited. We conclude by exploring four alternative potential outcomes for the future theory of change, each with different contributions to creating a more sustainable global seafood supply.