Thanks to Patrick Burns, Giles Heywood, and Gabor Grothendiec for responding to my question. Gabor suggested something along the lines of z <- ts(rnorm(25),start=as.numeric(chron("01/25/99"))) and then get back the times like this: chron(time(z)) To plot it: plot(chron(time(z)),z) Patrick and Giles suggested using the its library. In case anyone is interested, the following code created the time series that I needed: # Creating dates to associate with the time series dates.p33<-seq.dates(from="10/01/1952", length=dim(stageP33)[1], by="days"); # The next line insures that the dates start in 1952 rather than 2052 dates.p33<-format(as.POSIXct(dates.p33+1), "%m/%d/%Y") # Combining dates with data p33.its<-its(x=as.matrix(stageP33), dates=as.POSIXct(x=strptime(as.character(dates.p33),format="%m/%d/%Y")), names=dimnames(stageP33)[[2]],format=its.format()) I don't claim that is the best way to do it. Also note that this required the its and chron libraries. With regards, Brian