The competition for donations between charities is tough. Yet, little is known about how giving behavior is affected by competition between charities. Do people have a need to satisfy their demand for giving by contributing to a particular charity? Or can the demand for doing good be satisfied by giving to any organization? In a donation dictator game, I vary competition between charities by i.) altering the set of similar real charities to which subjects can donate and ii.) changing the relative price of giving to a randomly selected charity in the choice set by introducing a matching grant. I find weak substitution between charities when giving to more than one charity is possible, as the donated amounts to individual charities decrease with the size of the choice set. At the same time, aggregate giving to all charities increases when charities are in competition. Intensified competition through an increase in the charitable giving market seems to attract new giving. A reduced price of giving to one charity (matching grant), however, only increases giving to the matched charity. Price competition does not attract new donations as subjects substitute part of their own contributions with the matching grant and leave their total contributions unchanged.