This is a study in chronic stable Schizophrenia with the purpose to answer the question of whether agonism of the nicotinic alpha7 receptor is capable of enhancing cognition in a well defined chronic stable patient population treated with antipsychotics as standard of care, and thus to support the future development of AQW051 for the treatment of cognitive impairment associated with Schizophrenia (CIAS).

Inclusion Criteria:

• Diagnosis of schizophrenia
• Symptomatically stable and currently treated with a stable regimen for at least 3 (three) months prior to dosing with one of the following second generation of antipsychotics: risperidone, paliperidone, quetiapine, ziprasidone, aripiprazole.
• Specific cognitive impairment
• Smokers and non-smokers

Exclusion Criteria:

• Current treatment with an anticholinergic or other agent known to adversely interfere with the cholinergic system, and/ or treatment with cholinesterase inhibitor within the last three (3) months prior to dosing.
• Current treatment with conventional antipsychotics (e.g fluphenazine, haloperidol) or clozapine.
• History of neuroleptic malignant syndrome.
• Diagnosis of substance abuse (other than nicotine) within the last month and alcohol or substance dependence (other than nicotine) within the last 6 months.
• Score 4 or 5 on the Suicidal Ideation item or any "yes" on the Suicidal Behavior item of the CSSR-S that is related to suicidal behavior occurring during the last 2 years

Other protocol-defined inclusion/exclusion criteria may apply