Does parenthood impair workers’ on-the-job productivity? We study this question and its implications for understanding the child penalties in employment observed for mothers. We focus on judges, a profession that helps overcome key empirical challenges: output can be measured precisely, it can be observed for all workers before and after childbirth because virtually no parent leaves the profession, and workloads are evenly distributed, limiting scope for selective task allocation. Using a difference-in-differences design, we find no evidence that mothers’ -- and fathers’ -- output declines during pregnancy or after they return from parental leave, and we can rule out moderate declines. We validate this result using a broad set of measures capturing both the quantity and quality of judicial work, and we document similar patterns for self-employed labor lawyers. Our findings show that motherhood need not reduce on-the-job productivity and suggest that, at least in some contexts, child penalties in employment may not be driven by lasting declines in on-the-job productivity.