Benthic macroinvertebrate colonization of 12 0.04-ha experimental ponds was studied for 1 yr. The ponds were filled in late January 1988 and artificial substrate samples were retrieved at 4-wk intervals from 25 February 1988 to 25 February 1989. The first organisms (Chironomusand Ceratopogonidae) were collected in the first set of samples 4 wk after filling. The colonization sequence was Diptera (primarily several genera of chironomids), followed by Coleoptera, Ephemeroptera, and Odonata. The arrival of taxa corresponded to adult flight periods. Noninsect taxa (Oligochaeta, Nematoda, Amphipoda) were collected in relatively low numbers late in the year. Twenty-nine taxa were collected, 13 of which were present in all 12 ponds. Mean number of taxa, diversity, and evenness increased rapidly during the first 7 mo, but never became very high. Mean density increased slowly throughout the spring and summer to about 200 individuals per sampler and then increased rapidly during the autumn to about 600 individuals per sampler. Community structure was dominated by Chironomidae (≈85%) and Ephemeroptera (≈9%). Trophic function was dominated by detritus-feeding collectors (≈79%). Factors that influenced the structure and function of the new experimental ponds appeared to be: lack of connection to colonized waters, small size, and simple, homogeneous habitat and food resources.