Abstract We have cloned and characterized an insert of the Drosophila melanogaster genome chosen for study because it is homologous to RNA expressed more abundantly in early pupae than in embryos. This insert contains a cluster of five transcript coding segments within 8.5 kilobases. All of the transcripts that we describe are developmentally regulated, being at maximal abundance in late-third-instar larvae and early pupae, and not detectable or very rare in third-instar larvae about 1 day prior to puparium formation and in late pupae. Some of the transcripts are detectable at low levels in embryos. Unexpectedly, this cloned insert overlaps the previously described heat-shock gene cluster at cytological location 67B. Sequentially, we find a previously unknown coding segment within the heat-shock cluster, the two heat-shock coding segments, and two more previously unknown coding segments beyond the heat-shock coding segments. Thus, two genes which are induced by heat shock are also found to be expressed with the developmental regulation described above.