Objective: Few studies have examined psychological adjustment in thyroid cancer (TC) patients and no published studies have investigated benefit finding (BF) in this population. This study examined the relationship between BF and adjustment in TC using an expanded conceptualisation of adjustment that incorporated higher order cognitive and motivational states (HOCMS) and health behaviour changes, and a BF measure that accounted for positive and negative changes. Partner ratings of patient's BF and health behaviour changes were examined as sources of external validity for these constructs. Methods: 154 TC patients and 32 partners completed questionnaires. Results: Findings supported the prediction that BF would be associated with greater positive affect and positive health behaviour change, and better outcomes on the HOCMS of adjustment. After controlling for demographics and cancer stress, BF evidenced associations with greater positive affect, wisdom, spiritual wellbeing, and lifestyle changes. Conclusions: Results suggest that BF is related to health behaviour change that is corroborated by significant others and is strongly related to the existentially oriented adjustment outcomes. Copyright (c) 2011 John Wiley & Sons, Ltd.