Children involved in the foster care system are at risk of experiencing traumatic events, which can lead to negative outcomes for youth. Child welfare service providers are tasked with providing trauma-responsive services to youth in foster care; yet, the trauma-related needs of youth are often under-identified and undertreated. This study’s purpose was to examine the initial implementation of a trauma-responsive approach from the perspective of frontline child welfare workers and trainers. We sought to further knowledge on how the competency drivers of staff selection/hiring, training, coaching, and fidelity facilitate or inhibit initial implementation. We conducted focus groups with workers (n = 28) and semi-structured interviews with trainers (n = 6) implementing a new trauma-responsive assessment and case planning approach. Transcripts were coded and analyzed using thematic analysis. Using competency drivers as a guide, several facilitators and barriers were identified. Overall, workers and trainers identified each of the four competency drivers as key to the uptake of the new practice approach. Our findings highlight the need for agencies implementing new practices to provide critical supports to frontline workers during implementation, such as specialized support positions and mechanisms for structure and accountability, and emphasize the importance of post-training support (e.g., coaching).