This research will test theoretical models concerning the contributions of parental anxiety, environmental stress, child neurophysiological mechanisms, child behavioral reactivity to novelty and specified parenting behaviors towards the development of increasing difficulties with anxiety in young children. Two hundred and forty 2 year-old children (approximately one-third with anxiety in the clinical range) will be studied through 5 years of age. Parents and other caregivers will complete questionnaires and interviews concerning a wide range of anxiety symptoms. Children will also be interviewed when they reach 5 years of age. At each age, child neurophysiological mechanisms and child behavioral reactivity to novelty will be investigated. Parenting behaviors will also be systematically observed. Analyses will examine alternative models, delineating the most important factors and mechanisms that contribute to increasing anxiety over time. Clarifying the pathways and factors that lead to the development of increasing difficulties with anxiety will provide crucial information for the innovation of intervention strategies. [unreadable] [unreadable]