Wnt/β-catenin pathway, the effectors of which are transcription factors of the LEF1/TCF family, is primarily associated with development. Strikingly, however, some of the genes of the pathway are schizophrenia susceptibility genes, and the proteins that are often mutated in neurodegenerative diseases have the ability to regulate β-catenin levels. If impairment of this pathway indeed leads to these pathologies, then it likely plays a physiological role in the adult brain. This review provides an overview of the current knowledge on this subject. The involvement of β-catenin and LEF1/TCF factors in adult neurogenesis, synaptic plasticity, and the function of thalamic neurons are discussed. The data are still very preliminary and often based on circumstantial or indirect evidence. Further research might help to understand the etiology of the aforementioned pathologies.