Parental mobile device use while parenting has been associated with reduced parental responsiveness and increased negative affect among children. However, it remains unclear whether it can interfere with the process of acquiring social communication skills. Thus, this study sought to experimentally examine whether maternal mobile phone use while interacting with the child has an immediate effect on the frequency of mothers' and infants' joint attention (JA) behaviors, the likelihood that these behaviors will lead to JA episodes, and the duration of established JA episodes. Participants were a community sample of 114 (M[subscript age] = 11.36 months; 50% male) Israeli typically developing infants, in which most mothers were highly educated and living in two-parent families. Mother-infant dyads completed a modified still-face paradigm and were randomly assigned to one of three experimental conditions during the still-face phase: (a) mobile phone disruptions, (b) social disruptions, and (c) undisrupted play. Mother-infant interactions were coded for frequency of JA behaviors and duration of JA episodes. In dyads assigned to the mobile phone disruptions condition, infants produced more JA initiations, mothers were less likely to contingently respond to infant initiations, JA behaviors were less likely to result in established JA, and JA episodes were shorter compared to dyads in the two control conditions and the baseline free play phase. Findings suggest that maternal mobile phone use during face-to-face interactions with the infant can disrupt the process of establishing JA in ongoing mother-child interactions. Possible implications from this line of work for family digital media use are discussed.