Book excerpt: This book is open access under a CC BY 4.0 license. CRISPR-Cas9 is a rapid, efficient, versatile and relatively cheap method for dissecting the molecular pathways that are the basis of life, as well as for investigating and potentially rectifying faults in these pathways that result in disease. This book reviews how CRISPR-Cas9 and other genome editing techniques are advancing our understanding of development and function in the nervous system, uncovering the molecular causes of neurological disorders and providing tools for gene therapy.