I am plotting a cumulative plot of data with the fitted distribution's cumulative plot and I want to make it so that one or the other is in a different colour so that I can talk about which is which and, if possible, add a legend to the graph x = seq(0,30,0.01) plot(ecdf(IAT), do.point=FALSE, main = 'Cummlative Plot of Monday IATs\n for entire 15 Weeks') lines(x, pexp(x,0.41562500)) Many thanks Mark Miller