Establishing effective toothbrushing routines using fluoridated toothpaste in infancy has been suggested as important to dental health throughout childhood and into adulthood. However, previous studies have revealed a number of potential barriers to, and facilitators of caregivers ability to establish early dyadic toothbrushing routines with pre-schoolers. However, as yet no qualitative research has been conducted to ascertain potential barriers and facilitators of the earliest dyadic toothbrushing in infancy, and nor has any previous research specifically focused on how novice mothers of first-born infants and preschoolers manage this task. This study therefore outlines findings from a qualitative interview study with first-time mothers of children aged 24-30 months (n = 16) exploring perceived barriers to and facilitators of early dyadic toothbrushing routines with infants and preschoolers. A number of key themes were identified from interview transcripts and an 'ecological' approach conceptualised maternally perceived barriers to and facilitators of dyadic toothbrushing. Proximal influences were found to be located within the caregiver-child relationship ('micro-system'), including parental cognitions (e.g., PSE), parental behaviours (e.g., parenting practices) and infant and preschooler temperament and behaviours (e.g., tantrums). Distal factors were also identified as relevant to the establishment and maintenance of these routines, such as social support ('exosystem') and family history of tooth-brushing ('chronosystem').