Despite decades of promotion, rates of vegetarianism have changed minimally in the U.S. In part due to this slow growth rate, farmed animal advocates are divided about whether encouraging meat elimination or meat reduction (and which type) is best. Following Voltaire’s assertion that the perfect can be the enemy of the good, this research explores whether vegetarianism (the perfect) may be the enemy of the good for realizing advocates’ desired social movement outcomes in American society around meat and farmed animals. This dissertation, drawing on applied sociology and positioned at the intersection of effective altruism, social movement outcomes, the sociology of food, and dietary behaviour change, examines this research question and speaks to whether social movements should ask for intermediate steps or focus on their desired end goal. This dissertation engages with an effective animal advocacy lens—a subset of effective altruism—to study the current and future potential impact of three diets promoted to varying degrees by U.S. advocates: a vegetarian diet, a reduced-meat diet, and a chicken-free diet (per the problem of smaller-bodied animals). Quantitative methods were used to consider how these diets can help this social movement “do the most good,” a key tenet of effective altruism. Data was collected from an online census- balanced cross-sectional sample of 30,000+ U.S. adults provided by Nielsen in 2016. Results showed a reduced-meat diet had the highest prevalence rate among American adults and the largest number of food opinion leaders based on current as well as future potential eating patterns. A reduced-meat diet was the driver for the greatest number of meat-free meals eaten each week and the largest number of adults this is spread amongst, both taking in current and future potential trends. A reduced-meat diet also had the best external perceptions among those who are not restricting their meat consumption. Lived experiences was the one exception, where a vegetarian diet had the best internal experiences among individuals currently eating one of the diets. These findings suggest that there are reasons to infer that a reduced-meat diet may best support an effective animal advocacy approach to U.S. dietary outreach.