Developmental pathways are often regulated by multiple signals, and a major challenge is to understand how the different signaling pathways triggered by these signals interact to modulate a specific process. Brassinosteroids (BRs) are plant hormones that regulate cell expansion, cell division, and photomorphogenesis. A key regulator in BR signaling, the GSK3- and SHAGGY-like kinase BRASSINOSTEROID INSENSITIVE2, regulates two distinct steps in the stomatal development signaling pathway to either enhance or inhibit this process.