Methods: This study is comprised of a pre/ post-test quasi-experimental design evaluation of the ATTACH™ program as well as an examination of implementation feasibility via Normalization Process Theory (NPT). While Objective 1 will be addressed first, Objective 2 will begin soon after so that information gathered in Objective 2 may be used to tailor the implementation in Objective 1 as appropriate.

Research Question \& Objectives: The proposed research has the following two (quantitative and qualitative) arms: Objective 1 (Quantitative component): To evaluate community agencies delivered ATTACH™ impacts on: (1a) parent-child relationship quality, parental RF and child development, (1b) different patient populations (for whom program works best/worst), (1c) immune biomarkers indicative of inflammatory disease risk, i.e. gene expression and DNA methylation, (1d) health professionals' adherence to ATTACH™ program, via fidelity assessment, and (1e) outcomes 3 months post-intervention. Objective 2 (Qualitative component): To evaluate health care professionals' and administrators' perceptions and experiences of: (2a) intervention uptake and fidelity, (2b) implementation benefits, facilitators, barriers and challenges, and (2c) utility of ATTACH™ e-learning platform. The study participants can not be enrolled in the program without being in the research.

Objective 1: A quasi-experimental design was selected to more closely approximate service delivery models in agencies that do not typically employ control groups. We will intervene with 100 new patients and their birth to 36 month-old children, a sufficient sample size to detect minimum effect size (d=.34) for pre-intervention/post-intervention differences from the primary outcome of parent-child relationship quality, from the five community agencies. We plan to recruit 20 families (including parents, co-parents and children) from each agency.

Objective 2: NPT is used to uncover factors that interfere with the routine incorporation of interventions into health care. Thus, NPT is the ideal theory to guide our approaches including qualitative semi-structured interviews and analyses. NPT will enable the exploration of patients', health care professionals' and health system administrators' perceptions and experiences of intervention uptake and fidelity as well as the benefits, facilitators, barriers and challenges to ATTACH™ implementation by community agencies, including perceptions of the fidelity assessment tool and e-learning training.

Setting: Settings include Alcove Addiction Recovery, CUPS Calgary, Discovery House Women's Shelter, Sonshine Community Centre, and Steinbach Family Resource Centre, MB. Other interested agencies will also be involved. Patients, health care professionals and administrators from each agency will be recruited via convenience sampling methods to take part in one-on-one interviews. We plan to recruit 20 patients, 20 health care professionals and 20 administrators (total n= 60) at the participating agencies. However recruitment and data collection will continue until theoretical data saturation, i.e. the degree to which new data repeats or is redundant with what was expressed in previous data. We will employ a stopping rule: Data collection in a category (patient, health care professional, and health care administrator) will cease when three interviews in a row offer less than 5% new information. Only deidentified data will be sent by the participating agencies. Basic demographic data will be collected from stakeholders (patients, health care professionals, and administrators), including age, sex, employment and education. Using NPT in implementing complex interventions like ATTACH™, requires development of an interview guide addressing the four NPT concepts: coherence (meaning and sense making of ATTACH™ by participants), cognitive participation (commitment and engagement by participants), collective action (work the participants do to make ATTACH™ function), and reflexive monitoring (reflection of ATTACH™).

In finalizing the interview guide and developing the interview processes (e.g. home or clinic setting, telephone/web-conference, Zoom or in-person), the Patient Engagement Committee (PEC) and Community Engagement Committee (CEC) members will be engaged in review, feedback and decision making. The interview guide will be used for staff and patients and will be pilot tested before use. Interviews will be audio-recorded and transcribed verbatim with appropriate privacy protections in place to guard participant identity and personal information. Data analysis will occur in two parts. First, interviews will be transcribed and coded as soon as interviews are completed and examined for "nuggets" or key learnings that offer guidance to implementation in agencies. These nuggets will be shared with the Executive Team, PEC and CEC (especially relevant agency health care professionals and administrators) and discussed so that appropriate adjustments may be made to facilitate ATTACH™ normalization in agencies. Second, all transcripts will be coded using the stages of thematic analysis including familiarization, coding, theme development and data reporting. Theme and sub-theme development will be deductive, using a priori codes dictated by interview questions in order to explain factors that promote or inhibit interventions from being embedded in agency practice. As new interviews are undertaken, data will be examined to determine degree of data saturation. Two trainees will code the data, supervised by Letourneau, who is experienced in qualitative data analysis. Inter-rater reliability will be assessed and reported with Cohen's kappa coefficients; disagreements will be resolved by consensus. Data will be managed with QSR International NVivo12. Once themes and sub-themes are finalized, findings will be summarized in a draft report and shared with key informants as a validation check.