Gliomas are the most common type of primary brain tumour and are often fast growing with a poor prognosis for the patient. Their complex cellular composition, diffuse invasiveness and capacity to escape therapies has challenged researchers for decades and hampered progress towards an effective treatment. Recent molecular characterization of tumour cells combined with new insights into cellular diversification that occurs during development, and the modelling of these processes in transgenic animals have enabled a more detailed understanding of the events that underlie gliomagenesis. Combining this enhanced understanding of the relationship between neural stem cell biology and the cell lineage relationships of tumour cells with model systems offers new opportunities to develop specific and effective therapies.