This paper examines the impact of unilateral tariffs on the world growth rate through changes in tariff revenue and labor reallocation in a two-country endogenous growth model when firms are internationally mobile. In particular, in contrast to the effects of small deviations from free trade, this paper considers the effects of tariff increases given initial positive tariff rates. This paper finds that the growth effect of a unilateral tariff increase is pro-growth at high barriers levels, such as higher tariffs, but anti-growth at low barriers levels, such as low or zero tariffs.