Poverty is associated with experiences that can powerfully shape a child’s development and health. Young children growing up in poverty tend to score lower on measures of cognitive and socio-emotional development and are at high risk for developing multiple forms of psychopathology across their lifespan (Evans & English, 2002; Miller, Machlin, McLaughlin, & Sheridan, 2021; Peverill et al., 2021; Reiss, 2013). One avenue by which poverty may contribute to these disparities is by altering the function of brain systems that support emotion processing in children (Farah, 2017; Hao & Farah, 2020; Noble & Giebler, 2020). A well-established measure of emotion processing is frontal alpha asymmetry (FAA), an index of the relative difference between left and right alpha activity over frontal regions of the brain derived from electroencephalography (EEG; Davidson, 2000; Harmon-Jones, Gable, & Peterson, 2010; Reznik & Allen, 2018). FAA is thought to reflect individual differences in approach and avoidance/withdrawal motivational tendencies across development, such that higher FAA (i.e., greater left vs. right frontal cortical activity) is associated with increased positive affect and better emotional regulation abilities, whereas lower FAA (i.e., greater right vs. left frontal cortical activity) is linked to greater negative affect and less skill at emotion regulation (Coan & Allen, 2004; Cuevas & Bell, 2022; Marshall & Fox, 2007; Reznik & Allen, 2018). Additionally, young children with lower FAA tend to show greater internalizing behaviour (Baving, Laucht, & Schmidt, 2002; Perizzolo et al., 2017; Santesso, Reker Dana, Schmidt, & Segalowitz, 2006; Fox, Schmidt, Calkins, Rubin, & Coplan, 1996) and there is evidence that lower FAA can predict the onset of depression and anxiety in adolescents and adults (Blackhart, Minnix, & Kline, 2006; Nusslock et al., 2011; Pössel, Lo, Fritz, & Seemann, 2008; Stewart & Allen, 2018). Combined, these data suggest that FAA may be an early life marker of risk for emotional dysfunction and psychopathology. A large body of research further suggests that exposure to socioeconomic disadvantage, as well as to other forms of adversity (e.g., institutionalization, childhood maltreatment, foster care, challenging parenting behaviour, and parental depression), is associated with lower FAA in children and adolescents (Blaisdell, Barker, Giuliano, & Fisher, 2020; Hane & Fox, 2006; Hane, Henderson, Reeb‐Sutherland, & Fox, 2010; Miskovic, Schmidt, Georgiades, Boyle, & MacMillan, 2009; Peltola et al., 2014; Tomarken, Dichter, Garber, & Simien, 2004) and interventions that reduce deprivation are related to higher FAA in children (McLaughlin, Fox, Zeanah, & Nelson, 2011), suggesting that poverty may enhance risk for psychopathology by altering FAA early in life. Despite correlational evidence linking socioeconomic disadvantage and other forms of early life adversity to FAA, it is not clear whether poverty reduction may have a causal impact on FAA in young children. To address this gap, this study will leverage data from the Baby’s First Years study (BFY; https://www.babysfirstyears.com/). BFY is a longitudinal, randomized control trial in which 1000 mothers experiencing poverty were randomized to receive either high ($333 USD) or low ($20) monthly cash gifts for the first several years of their child’s life. A detailed description of the BFY study design can be found in Noble et al. (2021) and in the BFY preregistration on clinicaltrials.gov (identifier: NCT03595546). Predictions about intent-to-treat (ITT) impacts on infant resting brain activity in four frequency bands (i.e., theta, alpha, beta and gamma) were pre-registered and findings from these analyses were recently published (see Troller-Renfree et al., 2022). The current pre-registration will build on this work by investigating ITT impacts on FAA, a robust correlate of emotional processing and promising marker of risk for psychopathology, in infants. Additionally, we will examine whether individual differences in FAA are associated with concurrent socioemotional development in infants from the low-cash gift (i.e., control) group. Data for the current study will be drawn from the BFY baseline survey and Age-1 assessment.