Using a modified still-face procedure the present study explores 3-6-month-old infants' behavioral and physiological responses to mothers' screen distractions during mother-infant interactions. In the modified phone still-face procedure the neutral face of the traditional still face procedure was replaced with mothers' texting on their mobile phones. Infants' cortisol stress responses to mothers' device use were assessed through the collection of 3 infant saliva samples. Infants' behavioral responses including facial expressions, vocalizations, gaze and self-comforting behaviors were also explored. All mother-infant interactions were videoed recorded and coded for analysis. Thirty-four mother-infant dyads participated, average ages for mothers was 29 years and 4.4 months for infants. As predicted, infants demonstrated the changes in affect associated with the still-face effect, with significant differences in positive and negative affect during the play phases and the phone still face phase. As a whole, infants did not respond with increased cortisol responses, however, when individual differences were explored 47% responded with increased stress during mothers' phone distractions. Mother's frequency and attitudes towards device use were also assessed but were unrelated to infant responses. Implications and directions for future research are discussed.