The past decade has witnessed a growing interest in the trophic effects of antidepressant drugs. Antidepressants stimulate the production and signaling of plasticity-related proteins such as neurotrophins and cAMP response element binding protein, and neurotrophin signaling appears to be both sufficient and necessary for antidepressant action in rodents. Furthermore, several different antidepressant treatments increase neurogenesis in rodent hippocampus and this effect correlates with the behavioral effects produced by these drugs. These data suggest that antidepressants facilitate activity-dependent selection of functional synaptic connections in brain and, through their neurotrophic effects, improve information processing within neuronal networks compromised in mood disorders.