Steroid hormones coordinate many aspects of growth and development in metazoans. In insects, ecdysteroids, such as ecdysone, are made in the prothoracic gland (PG) and control moulting and metamorphosis, but little is known about the early steps of their biosynthesis from cholesterol. Niwa,Kataoka and co-workers now report that Neverland (Nvd) - a novel, conserved oxygenase-like protein - is required early in ecdysone synthesis and is essential for silkworm and Drosophila growth (see p. 2565). The researchers identified nvd by looking for genes predominantly expressed in the PG of silkworms. nvd is conserved in Drosophila, nematodes and several chordates (but not mammals), and the researchers show that loss of nvd function in the PG arrests growth and moulting in Drosophila larvae. This arrest can be rescued by the addition of active ecdysone or its precursor 7-dehydrocholesterol but not by cholesterol. Nvd proteins, the authors conclude, might be essential regulators of steroid synthesis and, consequently, of development both in insects and other animal phyla.