Schizophrenia is a common and severe, often disabling psychiatric illness of unknown aetiology that affects approximately 24 million people worldwide. The illness is characterized by symptomatology comprising positive symptoms (hallucinations and delusional behaviours), negative symptoms (anhedonia, social withdrawal and apathy) and cognitive dysfunction (diminished capacity for learning, memory and executive function). Current pharmacological treatments are effective at alleviating positive symptoms but have limited impact on negative symptoms and cognitive deficits. Furthermore, the extrapyramidal symptoms, hyperprolactinemia and metabolic syndrome, including substantial weight gain, are typical side effects limiting the value of many of these drugs for patients. Thus, drugs that better serve the patient population by effectively treating all symptoms with improved safety and tolerability remain a critical unmet need. Modulation of the metabotropic glutamate type 2 (mGlu2) receptor has emerged as a promising mechanism for the treatment of CNS diseases, with the potential to provide a new and more effective avenue for the treatment of schizophrenia.