as.Date.character has a format= argument but as.Date.factor does not which means that one can only use as.Date.factor if the factor labels have the default Date format. as.Date.factor just does a # as.Date.factor currently does this as.Date(as.character(x)) but for consistency's sake I think it should pass additional arguments such as format along: # as.Date.factor should do this as.Date(as.character(x,), ...)