While attributional style is regarded as a core domain of social cognition, questions persist about the psychometric characteristics of measures used to assess it. One widely used assessment of attributional style is the Ambiguous Intentions Hostility Questionnaire (AIHQ). Two limitations of the AIHQ include (1) a possible restricted range resulting from too few and too homogenous item scenarios, and (2) use of rater scores that are cumbersome and time-consuming to score and have unknown incremental validity. The present study evaluated the psychometric properties of the AIHQ while concurrently testing changes aiming to improve the scale, in particular expansion of the number of self-report items and removal of the rater-scored items. One hundred sixty individuals diagnosed with schizophrenia and 58 healthy controls completed the full AIHQ along with measures of symptoms, functioning, and verbal intelligence. The AIHQ particularly the self-reported blame score demonstrated adequate internal consistency, test-retest reliability, and distinguished patients from controls. It also was significantly related to clinically-rated hostility and suspiciousness symptoms, and correlated with functional capacity even after controlling for verbal intelligence. Incremental validity analyses suggested that a higher number of self-report items strengthens relationships to outcomes in a manner that justifies this expansion, while rater-scored items had mixed results in providing additional information beyond self-report in the AIHQ. (C) 2017 Published by Elsevier Ltd.