Cognitive interference control is disrupted in schizophrenia (SZ). Neuroimaging studies relate interference control to 4–7 Hz (theta) neural activity in a network spanning prefrontal, anterior cingulate (ACC), and parietal cortices. The mechanism of communication in this network and how it is disrupted in schizophrenia are unclear. Behavioral performance and EEG theta oscillations were examined in a Stroop color‐word interference task in 17 healthy controls (HC) and 14 SZ patients. Color‐word incongruence induced less theta power increase in SZ than in HC around 400 ms and 600–900 ms after word onset in ACC, left middle frontal gyrus (MFG), and inferior parietal regions. Coupling of ACC theta phase to MFG gamma amplitude, indexing interregional communication, was weaker in SZ than in HC. Results suggest ACC‐MFG theta power modulation as a mechanism of interference control that supports executive function and is disrupted in schizophrenia.