This paper examines the acquisition of both stable contextual variation and a change in progress by children aged four to twelve. Comparing children and their parents from 19 families, we investigate whether transmission and incrementation effects (Labov 2001, 2007) can be found in two vowel variables in Toronto English: /ae/-raising, a case of stable allophony, and /u/-fronting, an ongoing change. In /u/-fronting, children are extending the change to new, previously non-fronted environments. However, analysis does not reveal the expected incrementation pattern in which older children are more advanced. Instead we find the opposite: the youngest children are most advanced in the change, while the oldest are the most conservative, having retreated closer to the adult norm but still crucially further forward, allowing the change to progress. In the case of /ae/-raising, children are not extending the variation to new environments. Younger children do consistently overshoot the placement of /ae/ in raising environments, while older children appear to have retreated and stabilized in the same range as their parents, maintaining the contextual variation at the community level. We suggest that these patterns could be viewed as a kind of overgeneralization, similar to what is often seen in morphological acquisition.