The chapter explores psychotherapy process research with young children and their caregivers, highlighting the importance of understanding the mechanisms underlying therapeutic change. Although there is evidence of the effectiveness of early interventions, the research focused on the underlying processes of change, and their content is still scarce. The study of psychotherapy with young children and their caregivers faces methodological challenges due to young children’s communication styles and the complex dynamics between the child, their caregiver, and their relationship. Understanding change processes involves analyzing how interactions and experiences within therapy lead to transformations in the way children express their emotions and how caregivers respond to them. These changes do not always manifest explicitly, making it necessary to use approaches that help identify Changes in communication, emotional regulation, and the quality of the relationship between them. Although this kind of Research in Chile is pioneering has advanced the study of these Proceses using methodologies adapted from adult psychotherapy process Research. Psychotherapy process research in video-feedback intervention with young children has helped describe how therapeutic changes in young children are reflected in new parenting narratives and caregiver responses to child cues, And this chapter explains the first approaches to this kind of Research.