Erratum: In the article “Multiple Modes of Network Homeostasis in Visual Cortical Layer 2/3” by Arianna Maffei and Gina G. Turrigiano, which appeared on pages 4377–4384 of the April 23, 2008 issue, the incorrect version of Figure 5 was published. The correct version, displayed here, corresponds to the published figure legend and contains three additional panels.