WE PROPOSE A WORKSHOP WITHOUT WALLS ENTITLED "UPSTAIRS DOWNSTAIRS: CONSEQUENCES OF INTERNAL PLANET EVOLUTION FOR THE HABITABILITY AND DETECTABILITY OF LIFE ON EXTRASOLAR PLANETS" AND AN ACCOMPANYING SCHOOL ENTITLED THE "NEXSS WINTER SCHOOL".THE GOAL OF THE WORKSHOP IS TO INCREASE COLLABORATION BETWEEN GEOPHYSICISTS/GEOCHEMISTS AND ASTROPHYSICISTS STUDYING EXOPLANETS TO UNDERSTAND THE ROLE OF INTERIOR/SURFACE INTERACTIONS IN SETTING SURFACE CHEMISTRY AND ATMOSPHERIC BIOSIGNATURES.THE GOAL OF THE SCHOOL WILL BE TO HELP EARLY-CAREER SCIENTISTS GAIN SCIENTIFIC EXPERTISE AND AND UNDERSTANDING OF THE MAIN CONCEPTS AND TERMINOLOGY IN FIELDS WITHIN THE SCOPE OF THE WORKSHOP BUT OUTSIDE THEIR IMMEDIATE FIELD OF STUDY; TO PROVIDE BASIC SKILLS IN WRITING AND REVIEWING SCIENCE PROPOSALS; AND TO FACILITATE NETWORKING ACROSS DISCIPLINARY BOUNDARIES. STUDENTS WILL WRITE INTERDISCIPLINARY SCIENCE PROPOSALS BASED ON THE THEMES OF THE WORKSHOP AND WILL PARTICIPATE IN PRE- AND POST-WORKSHOP ACTIVITIES TO ASSESS THE PROMOTION OF INTERDISCIPLINARITY.