Pollen and seed viability tests were conducted with the native Celastrus scandens L and the naturalized C orbiculatus Thunb Mean pollen viability from three Connecticut sites was 48% for C scandens and 67% for C orbiculatus. At a fourth site a group of plants first identified as C orbiculatus had two different types of pollen (large viable and small nonviable) within single flowers. The possibility that these plants are interspecific hybrids is being investigated. Seed germination was 27% for C scandens and 71% for C orbiculatus In addition to high pollen and seed viability bird mammal and human dispersal are considered important in the rapid expansion of C orbiculatus populations in Connecticut and elsewhere.