We study financial efficiency in the nonprofit sector and document that organizations that rely mainly on commercial revenues are more efficient in managing their overhead and administrative expenses compared with nonprofits that rely mainly on donations. We also record a positive relationship between the extent of a nonprofit's reliance on donations and its efficiency in generating them. Our findings suggest economies of scale in the nonprofit sector and also a positive (negative) relationship between receiving government grants (membership income) and overall efficiency. We discuss what our findings imply for social enterprises and traditional nonprofits.