Growth cones regulate the speed and direction of neuronal outgrowth during development and regeneration. How the growth cone spatially and temporally regulates signals from guidance cues is poorly understood. Through a proteomic analysis of purified growth cones we identified isoforms of the 14-3-3 family of adaptor proteins as major constituents of the growth cone. Disruption of 14-3-3 via the R18 antagonist or knockdown of individual 14-3-3 isoforms switches nerve growth factor- and myelin-associated glycoprotein-dependent repulsion to attraction in embryonic day 13 chick and postnatal day 5 rat DRG neurons. These effects are reminiscent of switching responses observed in response to elevated cAMP. Intriguingly, R18-dependent switching is blocked by inhibitors of protein kinase A (PKA), suggesting that 14-3-3 proteins regulate PKA. Consistently, 14-3-3 proteins interact with PKA and R18 activates PKA by dissociating its regulatory and catalytic subunits. Thus, 14-3-3 heterodimers regulate the PKA holoenzyme and this activity plays a critical role in modulating neuronal responses to repellent cues.