This Funding Opportunity Announcement (FOA) encourages collaborative research applications on drug abuse and addiction that take advantage of special opportunities that exist outside the United States. Special opportunities include access to unusual talent, resources, populations, or environmental conditions in other countries that will speed scientific discovery. Projects should have relevance to the mission of NIDA and where feasible should address NIDAs international scientific priority areas (http://www.drugabuse.gov/international/research-priorities). While the priorities will change from year to year, in FY15 priority areas include: linkages between HIV/AIDS and drug abuse; prevention, initiation, and treatment of nicotine and tobacco use (especially among vulnerable populations such as children, adolescents, pregnant women, and those with co-morbid disorders); the neuroscience of marijuana and cannabinoids; and the effect of changes in laws and policies on marijuana and its impact. The R21 activity code is intended to encourage exploratory and developmental research projects by providing support for the early and conceptual stages of these projects. These studies may involve considerable risk but may lead to a breakthrough in a particular area, or to the development of novel techniques, agents, methodologies, models, or applications that could have a major impact on a field of biomedical, behavioral, or clinical research. Projects of limited cost or scope that use widely accepted approaches and methods within well-established fields are better suited for the R03 small grant activity code.