At the second North American Symposium on Bat Research the first reported use of radar to study flight behavior in bats confirmed that Mexican free-tailed bats (Tadarida brasiliensis mexicana) fly at altitudes over 3000 m above the ground. The reasons for these high-altitude flights were unclear, and it was assumed that the bats flew this high to commute to favorable foraging sites. Large numbers of insects now are known to utilize favorable winds at altitudes of hundreds to thousands of meters aloft to assist their long-distance movements. Dietary analyses and deployment of bat detectors to altitudes up to 1100 m confirm that Mexican free-tailed bats alter their behavior to feed heavily on these insects, many of which are major agricultural pests. Next generation radars confirm the movements and high-altitude intersection of bats and insects. Doppler weather radars continuously monitor and archive information on the emergence and dispersal of bats, providing long-term data on the bats’ ecology, behavior, and estimates of population sizes. Bat species regularly fly to high altitudes on all continents where they occur, and many of these bats are confirmed or suspected of feeding on migratory insects. The high-altitude habitat remains poorly known, as are the physiological adaptations, behaviors, and sensory cues that bats use to meet the challenges and opportunities of flying at high altitudes. Advancing technologies should continue to aid future research to investigate the high-altitude frontier and make discoveries about the ecology and behavior of bats aloft.