We use a unique data set for 115 countries, from 2000 to 18, and 5-year non-overlapping averages to explore the impact of technical assistance on revenue mobilization. To the authors’ knowledge, this is the first such effort to determine a direct relationship between technical assistance and the improvement in tax revenues. The paper finds that technical assistance significantly and positively increases tax revenues. Both income per capita and openness were found to positively improve the tax ratio in line with findings in the literature. Dynamic estimations also uncovered a long-run relationship among technical assistance, income per capita, openness, and tax revenues. This result further underscores that building capacity and institutional resilience takes time.