ABSTRACT We examine whether regional trade agreements (RTAs) facilitate international research collaboration. First, using a two-country model of a continuum of oligopolistic industries with process research and development (R&D) investment and spillovers, we analyze whether trade liberalization through a trade agreement with shallow or deep economic integration increases the number of firms that collaborate. We then empirically investigate the effects of shallow and deep RTAs by employing data on patents with multiple inventors from different countries at the United States Patent and Trademark Office for 114 countries/regions over 1990–2015. We interpret co-inventions by inventors from different countries as evidence of international research collaboration. We find that both shallow and deep RTAs are positively associated with research collaboration among member countries, and that the effect of deep RTAs on international research collaboration is stronger than that of shallow RTAs under certain conditions.