Background: Research on caregiver identity in the context of memory impairment has focused primarily on more advanced stages of the cognitive impairment trajectory (e.g., dementia caregivers), failing to capture the complex dynamics of early caregiver identity development (e.g., MCI; mild cognitive impairment caregivers). Objectives: The aim of this study was to develop a nuanced understanding of how caregiver identity develops in family and friends of persons living with MCI. Methods: Using constructivist grounded theory (ConGT), this study explored caregiver identity development from 18 in-depth interviews with spouses (n = 13), children (n = 3), and friends (n = 2) of persons recently diagnosed with MCI. Findings: The overarching themes influencing MCI caregiver identity development included MCI changes, care-related experiences, “caregiver” interpretation, and approach/avoidance coping. These themes influenced how participants primarily identified, represented as I am a caregiver, I am not a caregiver, or liminality (i.e., between their previous identity and a caregiver identity). Irrespective of their current self-identification, all conveyed thinking about their “future self,” as providing more intensive care. MCI caregiver identity development in family and friends is a fluid and evolving process. Nearly all participants had taken on care tasks, yet the majority of these individuals did not clearly identify as caregivers. Conclusions: Irrespective of how participants identified, they were engaging in care, and would likely benefit from support with navigating these changes and their new, ambiguous, and evolving roles.