A comparative study of butterfly communities in 15 urban/suburban remnants of tropical semideciduous forest in Campinas (São Paulo state, SE Brazil; 24°S, 47°W), with areas from 1.0 to 252ha and widely varying histories and environments, shows that the most significant factors, besides area and sampling time, distinguishing the sites and influencing their diversity (80–702 species) and composition are connectivity, permanent water, vegetation, flowers, and human impact (negative, including pollution). The diversified Nymphalidae butterflies (38–213 species) and especially two fermented-bait-attracted groups (Satyrinae, 2–30 species, and Biblidini, 9–44 species), are among the more useful indicators of the quality and diversity of the environments in these fragments. Effective conservation of butterfly communities in tropical cities may be achieved by maintenance of arboreal green corridors along streets and watercourses between moderately large (>10ha) humid areas, not near to the most built-up or polluted city centre(s), and the inclusion within these areas of ponds or streams, diversified native forest, and open vegetation including abundant nectar-rich flowers.