The correct architecture of dendritic trees is essential for the wiring and function of neuronal circuits. A number of cell extrinsic factors are known to regulate dendrite shape and patterning, but here Don van Meyel and co-workers show that the transcription factor Longitudinals Lacking (Lola) regulates expression of the actin nucleation protein Spire (Spir) to sculpt dendrite architecture in Drosophila (p. 650). The researchers show that Lola is expressed in dendritic arborisation (da) neurons of the Drosophila peripheral nervous system. They further demonstrate that Lola controls the number, growth and distribution of dendrite branches in da neurons. Loss of Lola also leads to increased expression of Spir, which in turn causes increased formation of abnormal and inappropriately positioned actin-rich branches. In line with this, the authors report that Spir promotes F-actin nucleation and regulates dendrite positioning. Together, these findings suggest that Lola acts to limit the expression of Spir within da neurons, thus ensuring balanced control of the actin cytoskeleton and regulated dendrite morphogenesis.