The islamic headscarf has been in the middle of heated debates in European society, yet little is known about its influence on day-today interactions. The aim of this randomized field experiment (n=840) is to examine if passengers standing on platforms of the Brussels, Paris and Vienna metros treat a confederate actress differently when she wears the islamic headscarf or hijab. Using a helping scenario and videotapes of the resulting interactions, it was measured whether passengers offered assistance and also various details of behavior that indicate interpersonal involvement. It was predicted that in interaction with the covered confederate less help would be offered, that women's level of nonverbal involvement would increase but men's decrease, and that responses would be stronger in Paris, intermediate in Brussels, and weaker in Vienna. The data were analyzed using Generalized Linear Models estimated with Bayesian inference. In response to the hijab, we find evidence of a lower probability of offering assistance in Paris, of increased involvement among women across sites, and of decreased involvement only in Paris and particularly among men.