– 38 – particular, the Atacama Large Millimeter Array (ALMA) will have the resolution and sensitivity needed to image these transition disks, using both the continuum and molecular tracers, at ∼ 1-3 AU resolution. Such exquisite observations will provide unprecedented observational constraints, much needed to distinguish among competing theories of planet formation. Finding promising targets for ALMA is one of the main goals of this paper, the first one of a series covering over 100 Spitzer -selected transition disks. Acknowledgments: We thank the anonymous referee for very helpful comments that improved this paper. Support for this work was provided by NASA through the Spitzer Fellowship Program under an award from Caltech. M.R.S thanks for support from FONDECYT (1061199) and Basal CATA PFB 06/09. G.A.R. was supported by ALMA FUND Grant 31070021. M.D.M. was supported by ALMA-Conicyt FUND Grant 31060010. J.P.W. acknowledges support from the National Science Fundation Grant AST08-08144. P.M.H. and N.J.E. thank the support from the Spitzer Space Telescope Legacy Science Program, which was provided by NASA through contracts 1224608, 1230782, and 1230779, issued by the JPL/Caltech, under NASA contract 1407. This work makes use of data obtained with the Spitzer Space Telescope, which is operated by JPL/Caltech, under a contract with NASA. Facilities : Spitzer (IRAC, MIPS), SMA, CSO (Bolocam), VLT (Conica), CLAY (Mike), CFHT (Espadons), Du Pont (Echelle).