Why does the following incorrectly subtract 4 hours from times = 20:00:00? > date = "03/31/10" > times = "20:00:00" > as.POSIXct(chron(date, times, format=c(dates="M/D/Y", times="hh:mm:ss"))) [1] "2010-03-31 16:00:00 EDT Thanks, Paul [[alternative HTML version deleted]]