Social-emotional competence is an important component of child development. From a biological perspective, the emergence of social-emotional competence is accompanied by changes in the brain (Broomell et al., 2019; Grossman & Johnson, 2007; Grossman et al., 2007). As development proceeds, brain regions become more specialized and orchestrated into networks (Clarke-Stewart & Parke, 2014; Johnson et al., 2009), which allows for more complex social behaviors in toddlers compared to infants. The current study aims to provide better insight into the developmental trajectories of brain networks and their relation with children’s social-emotional competence. The frontotemporal network appears to be involved in children’s social-emotional competence through the process of inhibition (Broomell et al., 2019) and the frontoparietal network is related to social-emotional competence given its role in attention (Gao et al., 2015) and social cognition (Adolphs, 2003; van der Velde et al., 2021). Brain networks become optimized through the pruning of unimportant connections and by the strengthening of important connections, which allows for more efficient communication between brain regions (Clarke-Stewart & Parke, 2014). However, the developmental trajectories of these brain networks remain unclear (Broomell et al., 2019; Solis et al., 2021). The likelihood of communication between brain regions is reflected by functional connectivity (Toth et al., 2017), and can be assessed by EEG rhythms (Fell & Axmacher, 2011). One common technique is resting-state EEG (RS-EEG), which is a recording of brain rhythms while not performing an assigned task (Anderson & Perone, 2018). However, there is a lack of conclusive evidence about the early developmental trajectories of functional connectivity using RS-EEG (Anderson & Perone, 2021), as research is limited to older children (Boersma et al., 2011) or studies only examined age-related differences without a longitudinal design (Bell & Fox, 1996; Thatcher et al., 2008). The link with children’s social-emotional competence is also unclear. This study aims to provide a better understanding of the neurodevelopmental trajectories that are relevant to children’s social-emotional competence. Specifically, the alpha and theta rhythms will be addressed by RS-EEG in the frontotemporal and the frontoparietal network.