contributions.The award is intended to allow mid-career or later-stage researchers (Associate or Full Professor, or equivalent) to expand or make a transition in their research programs via a sabbatical leave or similar mechanism of professional development and then develop that research program in their own lab. This award will also enable the PI to acquire new scientific or technical expertise, facilitate the investigator’s competitiveness, and potentially lead to transformational impacts in molecular and cellular bioscience. The award would fund up to six months of PI salary during the first sabbatical or professional development year, followed by support for continued research for two subsequent years upon the PI’s return to normal academic duties. Requests for flexibility in the timing of the sabbatical or professional development year will be considered with appropriate justification. Please contact the cognizant program director for the solicitation. Through this solicitation MCB and NSF hope to develop a novel mechanism that will encourage investigators to expand and/or transition to new research areas aligned with MCB priorities, to increase retention of investigators in science, and to ensure a scientific workforce that remains engaged in active research. Highest funding priority is given to proposals that have outstanding intellectual merit and broader impacts, while proposals with weaknesses in either category (or those that are perceived as likely to have an incremental impact) will not be competitive.Proposals should also demonstrate a strong record of prior accomplishment, a compelling plan for professional development that will enable the PI to forge a new direction in their scholarship, and a strong rationale for why this support is needed for the PI to become competitive in the new research area. Support for the proposed transition from the PI’s department, described in a letter from the department chair or equivalent, will also be required. Proposals that do not describe a plan for a transition in research direction will be considered unresponsive. Proposals that are motivated to understand the molecular and cellular basis of disease and disease treatments are not appropriate for the Division and will be returned without review. Proposals addressing major open questions at the intersections of biology with other disciplines, such as physics, chemistry, mathematics, computer sciences, and engineering are of particular interest to the program.