留守儿童和流动儿童等处境不利群体的健康问题是近年来心理学研究的关注重点。研究发现，我国处境不利儿童的整体发展状况堪忧，在学业成绩、心理健康以及社会适应等方面存在较多问题。然而，现有研究大多探讨单一逆境对处境不利儿童心理健康的作用，鲜少关注不同类型逆境对儿童其他健康指标的影响。本报告针对上述不足之处，通过三个研究，整合个体和日常水平等多水平分析视角，来探讨不同类型逆境对处境不利儿童的生理、心理和行为健康的影响。研究一聚焦于个体重要的生理应激反应系统(即下丘脑-垂体-肾上腺轴，或HPA轴)，通过收集293名我国农村儿童青少年的日常皮质醇样本，运用多层次模型分析，结果显示早期亲子分离能显著影响留守儿童的日常皮质醇节律。研究二基于个体为中心角度，聚焦于中国流动儿童的歧视知觉经历，通过对385名流动儿童进行4次追踪测查(每次间隔半年)，采用潜增长混合模型分析，研究发现流动儿童四种不同的歧视知觉轨迹类型(低稳定、下降、高稳定和上升)，而且不同组之间在心理和行为健康呈现出显著差异。研究三整合个体和日常水平分析视角，通过两个子研究分别探讨了新冠疫情期间逆境和压力对处境不利青少年的影响，结果发现疫情相关压力能显著调节处境不利群体日常感知压力对其情绪的影响。综上，通过聚焦生理、行为和心理健康结果变量，本报告从多个角度、不同层面考察儿童青少年发展，能一定程度上丰富有关处境不利儿童健康的研究视角，对未来的干预实践提供了重要参考价值。

Prior research has observed compromises in academic performance, mental health, and social-behavioral adaptation among left-behind and rural-to-migrant children and youth in China. These findings, however, have primarily focused on mental health and single- (versus multiple-) level analysis. It is less clear about the impact of adverse experiences on other domains of health among these disadvantaged children and youth. Addressing this gap, a series of studies were conducted to examine how different types of adversities contribute to the physical, psychological, and behavioral health of disadvantaged children and youth. Study 1 examined hypothalamic-pituitary-adrenal (or HPA) axis functioning among Chinese left-behind children using multilevel modeling, and results suggested that prolonged parent-child separation was associated with left-behind children’s diurnal cortisol patterns. Study 2 investigated the latent profiles of perceived discrimination trajectories among Chinese rural-to-urban children and adolescents using mixture growth modeling, indicating four distinct patterns of perceived discrimination trajectories and significant group differences in children’s psychological and behavioral outcomes. Study 3 unpacked the impact of the COVID-19 pandemic on disadvantaged youth’s psychological and behavioral adaptation using both longitudinal and daily diary designs. Results observed that adolescents’ mental health risks and problem behaviors increased during the pandemic, and that pandemic-related stressful experiences moderated the associations between daily perceived stress and moods. To conclude, these studies contribute to the literature by examining the associations between distinct types of adversities and multiple domains of health among left-behind and migrant children and youth, which have important implications for intervention programs aimed at promoting health development of these disadvantaged groups.