The International Research Experiences for Students (IRES) program supports international research and research-related activities for U.S. science and engineering students. The IRES program contributes to development of a diverse, globally engaged workforce with world-class skills. IRES focuses on active research participation by undergraduate and/or graduate students in high quality international research, education and professional development experiences in NSF-funded research areas. The overarching, long-term goal of the IRES program is to enhance U.S. leadership in science and engineering research and education and to strengthen economic competitiveness through training the next generation of research leaders. This solicitation features two mechanisms; proposers are required to select one of the following tracks to submit their proposal. Track I: IRES Sites (IS) projects engage a group of undergraduate and/or graduate students in active high-quality collaborative research, in principle at an international site with mentorship from researchers at a host lab. IRES Sites must be organized around a coherent intellectual theme that may involve a single discipline or multiple disciplines funded by NSF. Track II: Advanced Studies Institutes (ASI) are intensive short courses with related activities that engage advanced graduate students in active learning and research at the frontiers of knowledge. ASIs typically range in length from ten to twenty-one days and, in principle, must be held outside the United States. For all IRES proposals, PIs are strongly encouraged to outline virtual, hybrid or other alternative approaches to strengthen and maintain international collaboration in the event travel is not undertaken, and/or in addition to travel. Track I: IRES Sites (IS) due dates: November 12, 2020 and September 21, 2021. Track II: Advanced Studies Institutes (ASI) due dates: November 9, 2020 and September 28, 2021.