The ascidian tadpole possesses a basic chordate body plan with a simple mode of development; almost all cells are restricted to a single tissue type by the 110-cell stage. On p. 4047, Imai and colleagues report, in a transcriptional survey of Ciona intestinalis embryonic development, that only 65 transcription factors are zygotically expressed at or before this 110-cell stage, implying that the ascidian requires only 65 transcription factors for larval tissue specification. To see how these transcriptional factors might operate in transcriptional networks, the authors next suppressed three genes essential for endomesoderm specification – β-catenin, FoxD and Fgf9/16/20 – then assayed for changes in the regulation of the transcription factors normally expressed in the early embryo. From this, the researchers were able to deduce possible regulatory relationships between transcription factors. They predict that this approach will lead to the construction of gene networks, revealing fundamental insights into chordate development.