CODA is a menu-driven set of S-Plus functions which serves as an output processor for the BUGS (Bayesian inference Using Gibbs Sampling) software. For a Bayesian analysis specified by the user, BUGS carries out Gibbs sampling and writes the requested series of simulated values (``chains'') to an ASCII text file. CODA may then be used to perform convergence diagnostics and statistical and graphical output analysis of the contents of these files. Text output from CODA is displayed on the screen and recorded in a file called CODA.LOG, which may be printed after exiting from CODA. Hard copies of the graphical output may be obtained directly by using the ``print'' option in the graphics device window, or by storing the image as a postscript file for future use. CODA may also be used in conjunction with Gibbs sampling output from users' own programs. Section §7 describes the file format required for such output to be read into CODA.