Parenting is a rewarding experience but is not without its challenges. Parents of Autistic children face additional challenges, and as a result can experience lower levels of wellbeing and more mental health problems (i.e., depression, anxiety, stress). Previous studies have identified concurrent correlates of wellbeing and mental health. However, few have investigated predictors of subsequent wellbeing and mental health, or of change over time, among parents of pre-school aged autistic children. We examined child-, parent-, and family/sociodemographic factors associated with change in parents’ mental health and wellbeing across three timepoints (spanning approximately one year) among 53 parents of Autistic pre-schoolers (M = 35.48, SD = 6.36 months. At each timepoint, parents reported lower wellbeing and greater mental health difficulties compared to normative data. There was no significant group-level change over time in parent outcomes. However, individual variability in short-term (~ 5 months) wellbeing and mental health change was predicted by a combination of child- and parent-related factors, while variability in medium-term (~ 10 months) change was predicted by parent factors alone. Parents’ description of their child and their relationship predicted change in both wellbeing and mental health. Furthermore, participating in a parent-mediated intervention (available to a subgroup) was a significant predictor of change in wellbeing. Our findings highlight potentially modifiable factors (e.g., learning healthier coping strategies) that may positively impact both short- and medium-term change in parental outcomes.