Over time, people who spend a lot of time together (e.g., roommates) begin sounding alike. Even over the course of short conversations, interlocutors often become more acoustically similar to one another. This phenomenon -- known as phonetic alignment -- has been well studied in adult interactions, but much less is known about alignment patterns in intergenerational, adult-child dyads. In the current study, we investigated alignment between mothers and their children in a picture-naming task, as assessed using a perceptual similarity task and acoustic measures. Experiments 1 and 2 examined alignment in 2.5- and 4-year-old children and their mothers, both when mothers shadowed their children (Experiment 1), and when children shadowed their mothers (Experiment 2). Experiments 3 and 4 investigated long-term similarity between mothers and children when they were recorded separately. Results show that children and mothers aligned to one another in the shadowing task, regardless of who shadowed whom, and while there was no evidence for long-term alignment in younger children, there "was" some evidence of long-term alignment with 8-year-old children and their moms, but only for male children.