Externalizing behavior problems in early childhood are a highly relevant public health concern, with disruptive behavior disorders being the most common reason for referral to child mental health clinics in the United States ^[1][2][1,2]. Common externalizing behavior disorders, such as attention-deficit/hyperactivity disorder and oppositional defiant disorder, have been associated with increased risks of adverse outcomes in academic achievement, comorbidity with other mental illnesses and substance abuse, and criminality [3]. In addition, populations with marginalized identities and systemic disadvantages are reported to have higher rates of disruptive behavior disorders and have higher likelihoods of comorbid psychosis, depression, and substance abuse [4]. The non-transient nature of infant–toddler behavioral problems highlights the importance of intervention as early as possible to effectively reduce the need for more intensive treatments later in life ^[5][6][5,6].

A unifying theme across the theories of child development is the critical role of the primary caregiver. With this in mind, one of the most common methods for managing childhood behavioral problems is parenting interventions. Numerous parenting intervention programs have been developed that have demonstrated efficacy in the reduction of externalizing behaviors ^[7][8][7,8], with parent–child interaction therapy (PCIT) being one of the most highly researched and established evidence-based treatments for children who display disruptive behaviors as young as 3 years old [7]. The structure of the original intervention consists of weekly, hour-long, in-lab/clinic sessions across two phases of treatment. In the child-directed interaction (CDI) phase of treatment, parents are coached on improving the parent–child relationship during child-led play by increasing external displays of parental warmth and decreasing attention to child tantrums and negative behaviors. Therapists coach parents to use various do skills (i.e., praising appropriate behaviors, imitating appropriate play, etc.) and don’t skills, such as acknowledging inappropriate behavior, giving commands, asking questions, and being critical. To reach the skill criteria of the CDI-phase, caregivers must exhibit a sufficient number of do skills and a minimal number of don’t skills before moving on to the second phase of PCIT: parent-directed interaction (PDI). In the PDI phase, therapists teach caregivers to efficiently and appropriately give commands and increase child compliance, and treatment is considered complete once caregivers have achieved the skill criteria of both phases.

Despite their effectiveness, the dropout rates of parenting programs are high ^[9][10][9,10], and sociodemographic risk factors increase the likelihood of a poorer response to PCIT [11]. A limitation of the traditional PCIT training model is the strict skill criteria, which can take a significant amount of time to meet. In one large study, 25% of families who graduated from PCIT took an average of 20.5 weekly sessions to achieve the skill criteria, with a range of 5 to 71 sessions [12]. In ethnic minority populations, it has been suggested that the timeline is even longer (i.e., 18 weeks longer) due to cultural differences in the adoption of the Western norms that PCIT tends to encourage ^[13][14][13,14], adding another layer of difficulty for families to achieve skill criteria status.

To increase the accessibility and effectiveness of PCIT and decrease dropout rates, many variations have been developed to reduce the time commitment and incorporate more culturally relevant methods. Adaptations are especially relevant given the demonstrated differences in skill acquisition and the logistical barriers of attending an indefinite number of sessions. For example, Spanish-speaking Latina mothers were found to use significantly more don’t skills than English-speaking Latina mothers post-treatment and during follow-up [15]. Additionally, Spanish-speaking PCIT therapists have been found to significantly differ in their total verbalizations and their use of directive and responsive coaching in comparison to English-speaking PCIT therapists ^[16][17][16,17]. One way to address the logistical barriers of completing traditional PCIT is by focusing treatment on the child-directed interaction (CDI) phase of PCIT, halving the required time commitment. The CDI phase alone has shown effectiveness in ethnically diverse and low socioeconomic status samples in the United States ^[14][18][19][14,18,19], as well as with Latine toddlers as young as 12 months with externalizing behavior concerns [20].

Despite efforts to increase engagement with PCIT, various risk factors have been identified that reduce the effects of the intervention, many of which can be traced to systemic disadvantages, disproportionate stressors, and individual characteristics. For example, low socioeconomic status (SES) and maternal education are significant predictors of dropout from behavioral parenting interventions [21], and maternal intellectual functioning predicted 83 percent of families that dropped out of PCIT [13]. In addition to low SES, single-parent status and negative life stress predicted over 70 percent of poor parenting intervention outcomes one year after treatment ^[22][23][22,23]. Parental stress, in particular, has received recent attention due to its positive associations with child internalizing and externalizing behavioral concerns ^[24][25][24,25] and the interaction between mother–father stress and the risk of child abuse [26].

Identifying with a racial or ethnic minority status similarly places people at a higher risk for adverse outcomes. For example, Black youth are more likely to be diagnosed with externalizing behavioral disorders in comparison to White youth, who are more likely to be diagnosed with adjustment disorders [27]. Similar discriminant patterns are evident in the diagnosis of learning disabilities and other disorders relevant to child development in Black and Latine populations ^[28][29][28,29].

When considering disparities, it is also important to acknowledge that risk factors are related to one another. For example, low SES and ethnic minority status are more likely to co-occur in Hispanic and Black populations earning USD 12,000 and USD 22,000 less than the average median household income in the United States, respectively [30]. This finding aligns with prior research showing that low socioeconomic status (SES) and ethnic minority group membership predicted nearly 73% of dropouts, while low SES and White identification predicted 80% of treatment completion [21]. Language barriers also pose significant obstacles to treatment engagement for Latine populations seeking health care [31].

Although most prior research examined the effect of each individual risk factor independently [18], there is evidence for better prediction of treatment outcomes and dropouts by combining individual risk factors of adverse treatment outcomes into one cumulative risk index. One such study found that participants with higher cumulative risk scores were significantly more likely to drop out from PCIT and be less responsive to treatment [11]. Another study on cumulative risk in parenting intervention outcomes did not find a significant relationship between cumulative risk and parent-reported problem behaviors after receiving the Family Check-Up intervention [32]. However, this study included children who were at risk for behavior problems, not those that were already exhibiting problematic behaviors. Additionally, no adaptations were made to improve accessibility and generalizability to diverse populations. Other studies have found a positive relationship between cumulative risk and child externalizing behavior such that higher levels of risk were associated with more externalizing behaviors [33], and multiple stressor groupings of 4 or higher predicted higher rates of externalizing behavior concerns [34].