Many private institutions serving public purposes use volunteer work that they must disclose in their reports. In this paper, 315 public benefit organizations in Poland (PBOs) and 315 charities in the UK are analyzed using statistical methods. Differences in the level of disclosure and the degree to which PBOs’ financial results depend on the number of volunteers are also described. The conclusion the research has offered is that UK PBOs operate on a wider scale and use volunteer work more frequently and that the Polish. Moreover, UK PBOs are not significantly different than Polish regarding the relationship between their financial results and the number of volunteers supporting their activities.