Kids SIP"smart"ER is a 6-month behavioral and health literacy intervention effective at reducing sugar-sweetened beverage (SSB) intake among middle school students and their caregivers in the rural Appalachian region. This exploratory mixed methods study utilized a convergent parallel design to assess participant acceptability of a school-based curriculum for students and a text messaging program for caregivers. Acceptability was assessed using surveys (873 students and 453 caregivers), five focus groups (34 students) and telephone interviews (22 caregivers). Quantitative data were analyzed descriptively, and qualitative data were content coded. On a 5-point scale, average quantitative survey acceptability ratings ranged from 2.7 to 3.3 among three student-rated questions and 4.1 to 4.2 among four caregiver-rated questions. Qualitative focus group findings suggested that students preferred curricular activities that were hands-on and involved social interaction, while caregiver interview results showed high acceptability of the text messaging program's design, including usability, content messages and personalization. Students and caregivers reported similar program benefits: increased knowledge of SSBs and health risks, increased awareness of SSB behaviors and support to make beverage behavior changes. Results from this study can be used to understand Kids SIP"smart"ER's effectiveness data, communicate the intervention's acceptability with stakeholders and plan for future implementation studies.