We examined interactions between baseline hypothalamic-pituitary-adrenal (HPA) axis and parasympathetic nervous system (PNS) activity in relation to executive functions (EF) in a sample (n = 1,005) of children in low wealth, nonurban communities at age 48 months. Salivary cortisol and respiratory sinus arrhythmia (RSA) represented baseline HPA axis and PNS activity, respectively. The interaction between RSA and cortisol predicted EF such that children with either lower RSA and lower cortisol, or higher RSA and higher cortisol had higher EF scores. These findings suggest a potential compensatory relation in which the PNS and HPA axis counterbalance each other to support cognition.