Populists enact dramatic change, does this penchant extend to foreign policy? While the literature assumes increasing nationalism and protectionism, few studies directly test whether populists produce tangibly different foreign policies. I analyze defense and trade policy to ascertain the substantive consequences of populist presidencies, using an innovative longitudinal cohort study (LCS) from contemporary Latin America. After discussing three populist waves (classical, neo-populist, and Bolivarian), I compare neo- and Bolivarian populists with their non-populist counterparts. The quasi-experimental research design includes six cases that are broadly representative of Latin America: Argentina, Chile, Colombia, Peru, Nicaragua, and El Salvador, splitting countries into cohorts of similar economic and social development. Among cohorts, there is a control group and a treatment group, permitting comparison among non-populists and populists. While I find little evidence of divergent military policies, populists occupy economic extremes of the policy spectrum, particularly when compared with non-populists. Policy variation among populists reflects the structural position of their country in the international economic system. In more developed countries, populists from both the left- and right-wing are more likely to reduce trade openness and erect tariffs. In less developed, smaller countries, the opposite occurs as populists embrace international trade and lower tariffs.