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\textbf{Abstract}: The time delays between point-like images in gravitational lens systems can be used to measure both cosmological parameters as well as dark matter  (sub-)structure within the lens galaxy. With the upcoming \emph{Large Synoptic Survey Telescope} (LSST), of order 1000 lens systems consisting of a foreground elliptical galaxy producing multiple images a background quasar will become available. In an effort to assess the present capabilities of the community to measure accurately the time delays in these strong gravitational lens systems, and to provide input to future LSST cosmology feasibility studies, we pose a ``Time Delay Challenge'' (TDC). The challenge is organised as a set of ``ladders,'' containing a group of simulated datasets to be analyzed blindly by participating independent analysis teams. Each rung on the ladder consists of a set of realistic mock observed lensed quasar light curves, increasing in complexity and realism to incorporate a variety of anticipated physical and experimental effects. The initial challenge described here has two ladders, TDC0 and TDC1. TDC0 has a small number of datasets, whose true time delays will to  be available on demand used  as training set by  the participating  teams set up their analysis pipelines, and make measurements accurate enough to qualify pipelines. The deadline  for participation in TDC0 is November 1st 2013. The teams that pass TDC0 will be be able to participate to the much more demanding  TDC1. TDC1 will  consists of several thousand lightcurves, to provide the statistical power required to make meaningful statements about the subpercent  accuracy that will be required  in the LSST era. In this paper we describe the simulated datasets in general terms; terms, we lay out  the structure of the challenge and we define the metrics that will be used to quantify the goodness-of-fit, efficiency, precision, and accuracy of the algorithms. The deadline for TDC1 is May 1st 2014. The  results for TDC1 from the participating teams will be presented in a forthcoming paper. {\bf (GGD: perhaps companion paper to be submitted after  theopening and  closingdates  of the challenge should be listed in the abstract...)} TDC1.