Colony multiplication of the Sumatran stingless bee Trigona (Tetragonula) laeviceps was observed from October 1980 to May 1982. Mass flights of several dozen males or of about 1000 workers were observed several times around nests whose workers had started scouting for new nest sites. Transport of building materials to a new daughter nest continued for about 20 days, but the entrance tube was not completed until arrival of a virgin queen. Mass flight of workers and males around the daughter nest continued for about 3 hours. Most workers of the mother colony participated in this mass flight and were observed to enter the daughter nest, following the virgin queen. After an overnight stay about half of them returned to the mother nest. The proportion of workers remaining in the daughter colony was about 30 percent when the daughter colony became virtually independent of the mother colony (about one week after swarming). Males' mass flight continued around the daughter nest for 2 days after swarming. The young queen was tightly surrounded by workers and made repeated buccal contacts with them for about 5 days after swarming. Oviposition also started one week later. The mother colony could produce another daughter colony about one month later. The most remarkable results are return to the mother nest of many workers which went to the daughter nest and the negligibly small amounts of building materials and food carried into the daughter nest, compared with the stocks in the mother nest. These points were compared with other species to clarify characteristics of the reproductive strategy of T. laeviceps.