Project Summary/Abstract Developmental language disorder (DLD) impacts approximately 7-10% of kindergarten-aged children (Norbury & Sonuga-Barke, 2017; Tomblin et al., 1997). Children with DLD may experience lifelong difficulties with language comprehension and use across contexts, such as social communication or academics (Bishop et al., 2017). Early language weaknesses are associated with adverse psychosocial outcomes later in life (Conti‐Ramsden et al., 2018; St Clair et al., 2011), as well as increased risk of conduct problems (Yew & O'Kearney, 2013). Similar to DLD, behavioral challenges early in life tend to be stable across development (Huesmann et al., 2009) and impinge on academic and social functioning (Gifford-Smith & Brownell, 2003; Kremer et al., 2016). Longitudinal data suggest that children's language plays a causal role in shaping their behavioral profiles across development (Bornstein et al., 2013; Petersen & LeBeau, 2020). However, the impact of child behavior on early interaction quality remains unexplored. This is problematic given that developmental theory (Bronfenbrenner & Morris, 2007) and empirical data (Fuchs et al., 2013; Muris et al., 2003) suggest that children's behavior may influence early parent-child interaction quality. The quality of early parent-child interactions is an important determinant of later child language ability (Hirsh-Pasek et al., 2015). Thus, the influence of child behavior on early interaction quality may be clinically relevant for language outcomes. The lack of data related to the impact of behavior on early interaction quality represents a critical gap in the evidence for early language interventions. The proposed project seeks to address this gap in the evidence by determining, within children at risk for persistent DLD between the ages of 2;6 – 4;0 (years;months), the impact of children's behavioral profiles on their communicative responsiveness during a naturalistic parent-child interaction (Aim 1). This project will also examine how children's behavior impacts their participation in an interaction across three contexts (Aim 2). Finally, this project will explore parent use of communication repair strategies during interactions with children who have typically developing or disordered language (Aim 3). These data will clarify the relationship between child behavior and early interaction quality within a population at risk for persistent DLD and will point to future research questions. This training grant will prepare the applicant for a future career as an independent researcher studying early language interventions. Through its inclusion of clinical trial instruction, advanced statistical training, as well as consideration of multicultural competence and implementation science, the proposed training plan will prepare the applicant for post-doctoral work. This plan also includes attending relevant conferences, which will support dissemination of findings and networking with potential colla...