The COVID-19 health pandemic has exposed the strong vulnerabilities of countries, including developing ones to shocks, and underlined the need for exploring ways to strengthen countries' resilience to future shocks. The current paper uses the dataset made recently available by the United Nations Conference on Trade and Development (UNCTAD) to examine (for the first time) the effect of productive capacities on economic complexity. The analysis further investigates whether Aid for Trade (AfT) flows matter for the influence of productive capacities on economic complexity in recipient-countries. The analysis uses a sample of 126 countries (including both developed and developing countries) over the period 2002-2018, and adopts the two-step system Generalized Methods of Moments (GMM) approach. Results have shown that productive capacities exert a positive effect on economic complexity over the full sample. However, the magnitude of this positive effect varies across different sub-samples, with Least developed countries (LDCs) enjoying the lowest magnitude of this positive effect. Furthermore, total AfT flows are positively associated with economic complexity, with LDCs enjoying a higher positive effect than other countries. Interestingly, total AfT flows exert a higher positive effect on economic complexity in countries that experience low levels of overall productive capacities. The latter finding highlights the need for donor-countries to scale-up AfT flows in favour of countries (such as LDCs) that are characterized by low levels of productive capacities. Finally, the empirical outcomes indicate that productive capacities enhance economic complexity in countries that receive higher amounts of total NonAfT flows.