The National Science Foundation's Interfacial Engineering program is seeking fundamental research proposals on atomic- and molecular-scale interfacial phenomena and engineering of interfacial properties, processes, and materials. The program is particularly interested in proposals that address chemical separations, biological separations, interfacial phenomena at engineered interfaces and surfaces, and nanoconfinement and engineered surfaces. Proposals should demonstrate the novelty and potentially transformative nature of the research, as well as its importance in terms of engineering science and potential impact on society or industry. The program encourages collaborative and interdisciplinary proposals, and prior to submission, applicants are recommended to contact the Program Director to ensure programmatic fit. Typical award durations are up to three years, with single-investigator budgets typically including support for one graduate student and up to one month of principal investigator time per year. Larger budgets should be discussed with the Program Director prior to submission. The program also considers proposals for Conferences, Workshops, Supplements, RAPID, EAGER, and GOALI projects, which can be submitted at any time after discussion with the Program Director.