In this paper we illustrate the potential of the repertory grid technique as an instrument for case formulation and understanding of the personal perception and meanings of people with a diagnosis of psychotic disorders. For this purpose, the case of James is presented: A young man diagnosed with schizophrenia and personality disorder, with severe persecutory delusions and other positive symptoms that have not responded to antipsychotic medication, as well with depressive symptomatology. His case was selected because of the way his symptoms are reflected in his personal perception of self and others, including his main persecutory figure, in the different measures that result from the analysis of his repertory grid. Some key clinical hypotheses and possible targets for therapy are discussed.