In the literature on privately provided public goods, altruism has been motivated by what contributions can accomplish (public goods philanthropy), by the pleasure of giving (warm-glow philanthropy), or by the desire to personally make a difference (impact philanthropy).Underlying these motives is the idea that individuals trust that their donations reach their goal. We revisit these models but allow for distrust in the institutional structuresinvolved. An important result we derive is that trust considerations determine whether crowding out is less or more than complete, and we thus open up possibilities in terms of the extent of crowding out not currently available.We also model socially motivated philanthropy when income-heterogeneous donors take trust and ability-to-pay into account. With ability-to-pay in social motivation, an important result we obtain is that low-income donors may contribute more than high-income donors (in both absolute and percentage-of-income terms), giving a potential theoretical foundation to the frequently observed "U-shaped" pattern of giving. 5 Administrative costs are just one piece of an individual's trust in a charity, but, other things equal, an individual is more likely to trust a charity with lower costs than a similar-goaled charity with high costs.FERRARA AND MISSIOS | 585