Astronauts in upcoming International Space Station (ISS) missions will encounter unique environmental, social, and mission-related challenges typical of long-duration missions (LDMs). The need for crew members to possess and display skills and behaviors needed for successful adaptability to LDMs led us to upgrade the tools and procedures (e.g., psychological tests, structured interview) we use for astronaut selection. Various validation techniques were used to link upgraded selection tools to critical skills needed for LDM missions. The results of these validation efforts showed that various personality and biodata test variables are related to expert and interview ratings of critical LDM skills. Upgraded selection tools better address the critical skills, demands, and working conditions of LDM missions and facilitate the selection of astronauts who will more easily cope and adapt to LDM flights.