Predictors of Problematic Media use in Middle Childhood: Project M.E.D.I.A Abstract Media are a normative part of life for most children and adults with most individuals spending several hours each day using various media devices. However, as many as 10% of adolescents and emerging adults develop an addictive or pathological use of media, which impairs their ability to function in daily life. Existing research on pathological media use has focused on adolescents and emerging adults; however, trajectories of both pathological and healthy relationships with media likely begin well before adolescence. It is necessary to study the trajectories of media use, and in particular problematic and healthy media use, earlier in child development. This will allow researchers to discover the precursors of problematic use before pathological use of media has developed. The long-term goal is to understand media-related problematic behavior in childhood and its contribution to the development of pathological media use later in life. Problematic media use in early childhood involves a host of likely precursors to later pathological media use, including a fixation on media, tantrums or crying when media is removed, and sneaking or lying about media. The objective of this particular application involves three specific aims (1) to determine how early parenting (technoference and parent-child relationship quality) is associated with problematic media use during middle childhood, (2) to examine how child media content (child-directed and exploitative) is related to problematic media use over time, and (3) determine the transactional nature of problematic media use and child behavioral outcomes (social competence and executive functioning) in early childhood. The central hypothesis is that early parenting (technoference and parent/child relationship) and low-quality media will be associated with child problematic media use during middle childhood and such behavior will be associated with negative child outcomes. We propose to explore these aims in a 3-year longitudinal study in early childhood (from ages 5.5 to 7.5 years), utilizing our cohort of 500 children we have been studying since birth. We will do this by using several innovative methods including the CAFE toolkit (passive sensing apps that track time spent using media, time use diaries), and EMA to capture problematic media use in the moment. The proposed research is significant, because this longitudinal project will examine how early parenting and child media content relate to problematic media across the middle childhood period. This knowledge will help researchers identify high-risk individuals that might benefit from early intervention aimed at changing the trajectory of media exposure, to balance media with other activities, and to increase healthy media use. This may reduce the number of individuals who develop a pathological relationship with media later in development.