BACKGROUND To develop a theoretical model explaining the longitudinal changes in the caregiving process for family caregivers of persons with mild cognitive impairment (MCI) in Taiwan. METHODS A longitudinal, grounded theory approach using in-depth face-to-face interviews and an open-ended interview guide. We conducted 42 interviews over a two-year period; each participant was interviewed at least once every six months. All participants were interviewed in their home. The participants total of 13 family caregivers of persons with MCI. RESULTS One core theme emerged: "protective preparation." This reflected the family caregiving process of preparation for a further decline in cognitive function, and protection from the impact of low self-esteem, accidents, and symptoms of comorbidities for the family member with MCI. Protective preparation contained three components: ambivalent normalization, vigilant preparation, and protective management. CONCLUSIONS Interventions to help family caregivers manage the changes in persons with MCI can reduce caregiver burden. Our findings could provide a knowledge base for use by healthcare providers to develop and implement strategies to reduce caregiver burden for family caregivers of persons with MCI.