The prevalence of childhood stress has repeatedly been shown to be high, with 'parental separation' and 'being bullied at school' as the most frequently reported stressors in the child's everyday life. This is quite alarming as children are most vulnerable to the adverse psychological and physiological health consequences of chronic stress exposure. Despite growing research interest in this field over the last years, literature falls short in providing an overview of methods to adequately assess stress in elementary school children (6-12 years old). This review describes questionnaires and interviews, as well as laboratory measurements of cortisol in biological samples (serum, urine, saliva and hair) as stress assessment methods in children, with the emphasis on epidemiological research settings. Major characteristics, strengths and limitations of these methods are established, examples of child-specific stressor questionnaires and interviews are provided and specific recommendations with respect to epidemiological research are formulated. In addition, hair cortisol as a potential biomarker for chronic stress (in children) is discussed more thoroughly. This review is meant to serve as a preliminary guide for health researchers new to this research area by reflecting on theoretical and methodological aspects in childhood stress assessment.