To identify parental influences affecting micronutrient supplementation in children and adolescents (2–18 years of age) with Celiac Disease (CD), a multi-method (survey, focus groups) study was conducted. A 35-item questionnaire consisting of open- and closed-ended questions was launched nationally via Canadian Celiac Association internet sites. Five focus groups were conducted using a semi-structured interview guide. The survey and semi-structured interview guide content was vetted for face and content validity. Thematic analyses were conducted on the focus group content and open-ended survey questions, and χ2 and Fischer’s exact analysis were performed on closed-ended survey data. Survey respondents were predominantly mothers (97%) of female children (80 F, 49 M) between the ages of 9–12 (31%) with CD, residing in western provinces (55%) with a combined family income ≥$100 000/year (63%). Seventy-seven percent of parental respondent’s children or adolescents consumed micronutrient supplements, for 1–5 years (52%), 7 days a week (65%), as both multi-vitamin and single vitamin preparations (40%). Parental influences on child micronutrient use included health beliefs and knowledge, parental supplement use, supplement characteristics, age of child (above or below 13 years), household routines, and provincial residential status (P < 0.05). Parents relied on health professional recommendation (69%; MD, RD) and the internet (21%) as sources of information regarding child micronutrient supplementation. Parental health beliefs and knowledge, socio-demographic factors, and practitioner recommendation influence micronutrient supplement use in children and adolescents with CD.