The prevalence of obesity remains high in American children aged 2-5 while one in three Head Start children is overweight or obese. The proposed study is designed to test the efficacy of an early childhood obesity prevention program which promotes healthy growth in predominantly Latino children in Head Start.

The program is a group clustered randomized controlled trial in partnership with two local Head Start organizations to address key enablers and barriers in obesity prevention in young children. The study has three specific aims:

1. To test the efficacy of the Miranos! intervention on healthy weight growth (primary outcome) in normal weight, overweight, and obese children.
2. To test the impact of the Miranos! intervention on children's physical activity, sedentary behavior, sleep, and dietary behaviors (secondary outcomes).
3. To evaluate cost-effectiveness of the Miranos! intervention.

Miranos! will be delivered in Fall and Spring (8 months) and followed by a summer health campaign.

Using a three-arm design, 12 Head Start (HS) centers in equal number will be randomly assigned to one of three conditions: 1) a combined center- and home-based intervention, 2) center-based intervention only, or 3) active control. The interventions will be delivered during the academic year (an 8-month [mo] period). A total of 525 3-year-old children (52% females; in two cohorts) will be enrolled in the study at baseline and followed prospectively one-year post-intervention. The first cohort will be recruited in summer 2018. The second cohort will be recruited in summer 2019.

Data collection will be conducted at baseline (T0), immediate post-intervention (T1), and 1-year post-intervention follow-up (T2) and include children's height, weight, accelerometry-based PA and sedentary behavior, TV watching and sleep by parent reports, gross motor development, dietary intakes, food preference. Information on family background, parental PA- and nutrition-related practices, parental weight and health behaviors, PA and nutrition policies and environments at the center and home, and costs associated with intervention delivery will be collected. The primary endpoint for the study is the BMI at the posttest immediately following the completion of the intervention (T1).

Recruitment: Participant recruitment will take place during summer by sending a recruitment packet to child's home. This packet includes: study information sheet, recruitment flyer, informed consent form, a letter from center director and study PIs.

Process Evaluation: The process evaluation is informed by the NIH Behavior Change Consortium Treatment Fidelity Workgroup's best practice recommendations and recent multi-component RCTs. Míranos! has multiple components with multiple activities, the investigators will use many indicators to evaluate the fidelity and completeness of the implementation of all components and determine contribution of each component by linking it to the primary and secondary outcomes. The investigators will collect both quantitative/qualitative data to assess cross-site treatment consistency, non-treatment-related effects, and document protocol changes.

First, intervention dose delivered will be measured by: 1) pre-/post-study center environmental assessment by the Environment and Policy Assessment and Observations (EPAO) and auditing of meal menus; 2) completion of delivery schedule of staff, peer leader training, parent education sessions, home visits; 3) evaluation of staff, peer leader training; 4) monthly auditing of weekly lesson plans; and 5) monthly checklist of use of Míranos! Activity Cards, children's story books, HHL learning activities.

Second, the intervention dose received will be assessed by: 1) attendance records of staff, peer leader training, parent education sessions; 2) certification test of staff, peer leader training; 3) monthly staff evaluation (rating scale) of children's learning of HHL content, gross motor skills, eating behaviors; 4) post-study parent intercept interviews; and 5) post-study focus groups on program delivery process with staff (n=24) and parents (n=32).

Third, participants' responses to the intervention will be evaluated by: 1) random observations of staff behavior (rating scale) during outdoor play and lunch by research staff; 2) assessments on children's PA by the System for Observing Fitness Instruction Time for Preschoolers and diet by group plate waste test in 3 randomly selected centers; 3) in-depth interviews with staff (n=48) for program feedback; and 4) post-study staff and parent evaluation (rating scale) of satisfaction with intervention components/activities.

Inclusion Criteria:

• The child must be enrolled in a full-day Head Start center
• The child must be 3 years old at baseline, one child per family, parental consent

Exclusion Criteria:

• N/A

All IPD collected will be shared

Data will become available after data has been analyzed for primary and secondary outcome measures

Data will be made available for research educational purposes.

The parents of the children were informed that their Head Start center will be randomly assigned to one of the three study groups.