With recent successes in characterizing standing postural stability of people with neurological disorders, Time-to-Boundary (TTB) measures have potential to provide deeper insights into the impacts of Parkinson’s disease (PD) and dual tasking on postural control. The TTB captures the critical relationship between the body sway and base of support, not incorporated into traditional stability measures. However, few studies have evaluated TTB in people with PD. The purpose of this study is to extend the existing work on how PD and a distracting cognitive task impacts standing postural stability. Different TTB measures were applied to data from fourteen PD and thirteen neurotypical adults (NA) subjects. Our results indicate that TTB measures are significantly worse in PD than NA subjects regardless of the existence of a secondary cognitive task. Further, medio-lateral TTB (but not anterior-posterior or 2-dimensional) was significantly negatively affected by the secondary cognitive task in both PD and NA groups.