THE STUDY OF BROWN DWARFS [OBJECTS TOO LOW IN MASS TO SUPPORT NUCLEAR REACTIONS IN THEIR INTERIORS] AND EXTRA SOLAR PLANETS REQUIRES A KNOWLEDGE OF THE PHYSICAL CHARACTERISTICS OF THEIR ATMOSPHERES IN ORDER TO INTERPRET OBSERVATIONS OR TO CONSTRUCT THEORETICAL MODELS. THE PURPOSE OF THIS PROPOSAL IS TO USE THE LATEST AVAILABLE DATA ON ATOMIC AND MOLECULAR TRANSITIONS TO GENERATE TABLES OF OPACITIES OVER A WIDE RANGE OF TEMPERATURES AND PRESSURES APPLICABLE TO THESE OBJECTS. THIS INVOLVES ASSEMBLING THE LATEST DATA ON VARIOUS ATOMIC AND MOLECULAR SPECIES AND GENERATING DETAILED OPACITIES USING THE BEST AVAILABLE INFORMATION ON SPECTRAL LINE SHAPE AND LINE BROADENING. A COMPLETE SUITE OF COMPUTER PROGRAMS NOW EXISTS TO CARRY OUT THESE TASKS AND NEW IMPROVEMENTS AND UPGRADES ARE ANTICIPATED AS A PART OF THIS PROJECT. CURRENTLY THIS DATA IS USED EXTENSIVELY TO GENERATE THEORETICAL MODELS AND TO INTERPRET OBSERVATIONAL DATA BOTH FOR OUR OWN GROUP AND FOR OUTSIDE COLLABORATORS. AS THE QUALITY OF THE OBSERVATIONS OF THESE OBJECTS IMPROVES DUE TO NEW AND IMPROVED INSTRUMENTS AND THE INTRODUCTION OF FUTURE SPACE BASED TELESCOPES IT WILL BECOME MORE IMPORTANT TO HAVE AVAILABLE THE BEST POSSIBLE OPACITY DATA THAT AS FAR AS POSSIBLE APPROACHES THE QUALITY USUALLY SEEN IN LABORATORY SPECTRA. A SOUND KNOWLEDGE OF THE CHARACTERISTICS OF THE SPECTRA OF THESE OBJECTS WILL INFLUENCE THE DESIGN OF FUTURE INSTRUMENTS INCLUDING SPACE BASED OBSERVATORIES SUCH AS WFIRST AND JWST AND GIVE A BETTER INDICATION OF WHAT THEY CAN BE EXPECTED TO ACHIEVE WHEN IN OPERATION.