To further scientific and technological cooperation between the United States and the European Community, the National Science Foundation and the European Research Council signed an Implementing Arrangement on October 29, 2019 to enable U.S.-based scientists and engineers with active NSF awards, particularly those early on in their careers, to pursue research collaboration with European colleagues supported through EU-funded European Research Council (ERC) grants. This letter invites current NSF grantees to submit supplemental funding requests for research visits to any identified, appropriate ERC-funded European research group. NSF particularly encourages requests from NSF grantees who are early on in their careers or who are still actively building their careers. Further, the letter gives instructions on how to submit supplemental funding requests and other relevant policies and requirements. The European hosts will provide funding to support in-country living expenses during the visits. NSF will provide travel funds to and from Europe. It is expected that the amount requested will not exceed $20,000, inclusive of any foreign travel expenses for qualified family members. This opportunity is open only to PIs and co-PIs of active NSF awards. Supplemental funding may not be used to support travel for senior personnel, postdocs, or others funded on the award. Please note, however, that NSF Postdoctoral Research Fellows with active Fellowships are eligible to submit to this opportunity. Requests must be received at NSF at least 3 months prior to the proposed visit, but no later than May 15, 2020, for consideration using Fiscal Year 2020 funds.