Brain-derived neurotrophic factor (BDNF) promotes CNS myelination, which is crucial for normal CNS function. This thesis investigates the influence BDNF and its signalling exerts upon myelination. Surprisingly, I found that conditional deletion of TrkB in oligodendroglia exerted no effect on myelination in vivo. However, over-expression of Erk2, a molecule activated by BDNF signalling, promotes myelination in vitro. I found that Erk1/2 interacts with and phosphorylates the oligodendroglial transcription factors Olig1 and Olig2, which may contribute to Erk1/2’s promyelinating effects.