As families increase their use of mobile touch screen devices (smartphones and tablet computers), there is potential for this use to influence parent-child interactions required to form a secure attachment during infancy, and thus future child developmental outcomes. Thirty families of infants (aged 9-15 months) were interviewed to explore how parents and infants use these devices, and how device use influenced parents' thoughts, feelings and behaviours towards their infant and other family interactions. Two-thirds of infants were routinely involved in family video calls and one-third used devices for other purposes. Parent and/or child device use served to both enhance connection and increase distraction between parents and infants and between other family members. Mechanisms for these influences are discussed. The findings highlight a new opportunity for how hardware and software should be designed and used to maximise benefits and reduce detriments of device use to optimise parent-infant attachment and child development. Practitioner Summary: Many families with infants regularly use smartphones and tablet computers. This qualitative study found that how devices were used either enhanced or disrupted feelings of parent-infant attachment. Practitioners should be aware of the potential beneficial and detrimental impacts of device use among families given implications for attachment and future child development.