Despite intense attention, the mechanisms regulating dendritic spine structure remain elusive. In this issue of Neuron, Jaworski and colleagues explore the morphological consequences of periodic spine incursions of dynamic microtubules and their associated protein, EB3. Microtubules, long thought to be absent from dendritic spines, are capable of controlling spine morphology, opening up a new line of investigation into mechanisms of spine plasticity and maintenance.