Written emotional disclosure (WED) is a self-directed, writing intervention. Treatment effects post-WED vary between studies, prompting research into which variables promote the largest improvements. Thus far, research has focused on the frequency of certain linguistic properties of the writing, and subjective stress-related ratings. This study tests the feasibility of using an objective coding framework for stress typology to categorise WED extracts and explores whether any characteristics of the stress described were associated with intervention outcomes. WED extracts from a randomised controlled trial of patients with asthma were coded using an objective stress typology framework. The contents of the WED extracts were reviewed to ascertain whether the experience met the DSM-5 definition for trauma, involved abuse, and was experienced directly or vicariously. Also analysed were the degree of upheaval and upset associated with the event described, together with the time of the event, and number of events written about. Correlational analyses indicated that improvements in asthma-related outcomes were associated with writing about experiences that occurred in childhood, constituted abuse, or caused greater upheaval (all ps <. 05). We found some evidence that the treatment effects of WED may be dependent on what types of stressful experiences participants write about. The use of our objective stress coding scheme was only partially successful as it could not be applied consistently to all WED extracts. Findings require replication using a prospective experimental design.