The Assessment and Measurement of Adult Life Stress: Basic Premises, Operational Principles, and Design Requirements Kate L. Harkness Queen’s University Scott M. Monroe University of Notre Dame Life stress is a central factor in the onset and course of a wide range of medical and psychiatric conditions. Determining the precise etiological and pathological consequences of stress, though, has been hindered by weaknesses in prevailing definitional and measurement practices. The purpose of the current paper is to evaluate the primary strategies for defining and measuring major and minor acute life events, chronic stressors, and daily hassles as informed by 3 basic scientific premises. The first premise concerns the manner in which stress is conceptualized and operationally defined, and specifically we assert that stress measures must not conflate the stress exposure with the stress response. The second premise concerns how stress exposures are measured, and we provide guidelines for optimizing standardized and sensitive indicators of life stress. The third premise addresses the consequences of variations in the procedures for life event measurement with regard to the validity of the research designs employed. We show that life stress measures are susceptible to several sources of bias, and if these potential sources of bias are not controlled in the design of the research, spurious findings may result. Our goal is to provide a useful guide for researchers who consider life stress to be an important factor in their theoretical models of disease, wish to incorporate measures of life stress in their research, and seek to avoid the common pitfalls of past measurement practices. General Scientific Summary Life stress is a key factor in causing disease. However, many of the most commonly used measures for assessing life stress lack adequate reliability and validity. This paper critically reviews stress measurement strategies and provides practical recommendations for incorporating the best stress measures into research designs. Keywords: chronic stress, daily hassles, measurement, stressful life events Theories pertaining to the origins of mental disorders, dating back centuries, commonly include a strong causal role for stress. Modern studies, using sophisticated prospective designs strongly support etiological effects of stress for many of these disorders (e.g., Brown & Harris, 1989; Cohen, Janicki-Deverts, & Miller, 2007; Kendler, Karkowski, & Prescott, 1999). Further, stress is an important contributing factor in the onset and course of many medical conditions, including cardiovascular disease, diabetes, and Alzheimer’s disease (e.g., Kershaw et al., 2014; Renzaho et al., 2014). Despite the promise of life stress for understanding the etiology and course of disease, research advances have been hin- dered by weaknesses in prevailing definitional and measurement practices. Today’s research agendas increasingly are being shaped by the groundbreaking scientific advances being made in the identification and assessment of biomarkers for many diseases (e.g., neuroimaging technologies, sophisticated epigenetic and pro- teomic assays). The environment crucially shapes biology and, thus, research examining their integration is poised to make enor- mous contributions to the understanding of disease etiology. How- ever, the measurement of life stress today relies largely upon research practices that are insufficient for addressing contempo- rary research questions in a scientifically sound and sensitive manner. The purpose of the current paper is to evaluate existing practices for defining and measuring life stress. We start by introducing three premises based on scientifically sound principles intended to help guide measurement practices and research in this domain. The first premise concerns the manner in which stress is conceptualized and operationally defined. Broadly considered, stress can be viewed as involving the environmental challenges to which an Editor’s Note. Constance Hammen served as the Guest Editor for this article.—SHG This article was published Online First June 2, 2016. Kate L. Harkness, Department of Psychology, Queen’s University; Scott M. Monroe, Department of Psychology, University of Notre Dame. Preparation of this review was supported by a grant from the Social Sciences and Humanities Research Council (435-2012-1536) awarded to K. Harkness, and a Fellowship from the John Simon Guggenheim Foun- dation awarded to S. Monroe. We thank Katrina Milani for help in the preparation of this manuscript. Correspondence concerning this article should be addressed to Kate L. Harkness, Department of Psychology, Queen’s University, Kingston, On- tario, Canada, K7L 3N6. E-mail: harkness@queensu.ca This document is copyrighted by the American Psychological Association or one of its allied publishers. This article is intended solely for the personal use of the individual user and is not to be disseminated broadly. Journal of Abnormal Psychology © 2016 American Psychological Association 2016, Vol. 125, No. 5, 727–745 0021-843X/16/$12.00 http://dx.doi.org/10.1037/abn0000178 727