The relationships among symptoms, cognitive functioning and social functioning were investigated in patients with schizophrenia over a period of 15 months. Patients with a mood disorder, a normal control group and a sample of parents of the schizophrenic patients also completed the cognitive tests. In the schizophrenia sample, only disorganisation was correlated with cognitive performance, which was interpreted as further evidence that disorganisation is a separate symptom dimension of schizophrenia. Against expectations, with two of three measurements no significant correlations were found between negative symptoms and cognitive performance. With these two measurements, however, a curvilinear association between negative symptoms and cognitive performance was observed, suggesting that negative symptoms are not a unitary concept. Finally, tentative evidence could be obtained for speed of information processing and selective attention as markers for vulnerability, although the latter is not specific for schizophrenia.