22 item questionnaire assess satisfaction with the relationship with the navigator and with the referred services to which the navigator facilitated access. Response scale: 1= Extremely Dissatisfied 2=Dissatisfied 3=Fairly Dissatisfied 4= Not dissatisfied nor satisfied 5= Fairly Satisfied 6= Satisfied 7= Extremely Satisfied. Higher scores indicate a better outcome.

Parent-reported satisfaction with family navigation using the Navigation Satisfaction Tool (NAVSAT).

The ECBI 36-item caregiver-report measure that assesses parent perceptions of frequency/severity of problem behaviors in their children/adolescent. There are two scales:

1. Intensity Scale: Measures the frequency behaviors reportedly occur. Items query "How often does X problem occur with your child? Responses rated on Likert scale from "(1) Never" to "(7) Always." Scoring: Responses to all 36 questions were added to derive the Raw intensity score (min.= 36, max.= 252). Cut-off for clinical significance: >/= 131.
2. Problem Scale: Secondary scale that measures degree to which behavior is problematic. Parents prompted to answer "Is this a problem for you?" with "(1) yes" or "(0) no." Scoring: Total "Yes" responses for the 36 items were added derive the Raw problem score (min.=0, max=36). Cut-off for clinical significance: >\= 15.

Because scores are weighted, higher scores that exceed identified clinical cutoffs reflect greater concern about the child's behaviors.

Baseline and Post: ECBI intensity scale raw score (Rows 1&2) and ECBI problem scale raw score (Rows 3&4) reported for child participants in the Standard FN condition and Tech Enhanced FN condition.

The Parent Activation Measures for Developmental Disabilities (PAM-DD) is 13-item measure used to examine changes in caregiver knowledge, skill and confidence to manage their child. The first subscale includes items related to the motivation and ability to actively intervene for one's child (e.g., ability to reduce problems, handle services, implement home treatments, understand behavior causes, use available treatments, implement recommendations, prevent problems, figure out solutions, and maintain changes). The second subscale contains items related to parental knowledge, cooperation, and agreement with treatment (e.g., responsibility for child's behavior, participation with treatment role). Respondents rate each item from (1) strongly disagree to (4) strongly agree. A higher score indicates a more positive rating (i.e., greater parent activation). Scores below reflect averages across items for each subscale (1 - 4) at baseline and post.

Multiple rows used to provide scores for PMADD at baseline and post. Subscales 1 and 2 reported separately.

The PPEM is a 5-item parent-report measure of active caregiver engagement in youth mental health services (Haine-Schlagel et al., 2016). Each item assesses the frequency that a parent engaged in a participation behavior (e.g., asked questions, provided input, agreed with the plan) during a MH appointment. Items are rated on a 5-point scale ranging from (1) Not at all to (5) very much.

Parent engagement was assessed at post using the 5-item, caregiver-report, PPEM (Haine-Schlagel et al., 2016). A mean score was used in analyses.

To additionally capture family engagement, the number of contact attempts (e.g., navigation sessions, texts, voicemail messages) between the navigator and each family during the interval between PCP referral to ATTAIN NAV (wherein a dyad was enrolled in family navigation following observation period) and the conclusion of ATTAIN NAV (end of a dyad's study participation) was calculated. These data were abstracted from the family navigation contact logs and include unsuccessful attempts.

Navigator fidelity was assessed using fidelity procedures (observational and self-report) from the navigator training curriculum used in previous autism-specific family navigation studies (Broder-Fingert et al., 2019, 2020). Navigators provided self-report fidelity ratings at three time-points: the Family Plan Development session (first navigation session), a follow-up session at the midpoint of family navigation, and the final session. Range: 0% - 100% "Fidelity" was defined as demonstrating mastery on at least 80% of components (e.g., navigator introduces purpose of navigation during initial contact, conducts assessment of barriers to attendance of first mental health appointment). A mean fidelity rating across the three sessions was computed for each family at post. Overall average for both conditions is reported here.

Navigators were not considered participants in this research study. Scores for navigator fidelity were provided at 3 time points for each family/dyad. A mean fidelity rating across the three sessions was computed for each family. Data reported here reflects the average navigator fidelity for the two study conditions.