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We present new BVI photometry for the halo globular cluster M5, and examinethe B- and I-band luminosity functions (LFs), based on over 20,000 stars. We donot see evidence in the LF of a ``subgiant excess'' or of a discrepancy in therelative numbers of stars on the red-giant branch and main sequence, both ofwhich have been claimed in more metal-poor clusters. Inclusion of alpha-elementenhancements improves the agreement between the observed and predictedpositions of the ``red-giant bump''. Using the \Delta V_{TO}^{HB} method, weconclude that the clusters M5, Palomar 5, M4, NGC 288, NGC 362, NGC 1261, NGC1851 and NGC 2808 are the same age at the level of about 1.5 Gyr, with thepossible exception of NGC 288 (older by 3.5\pm 1.5 if the reddest NGC 288 HBstars are on the zero-age horizontal branch). Even with NGC 288 set aside, thelarge range in HB morphology in the remaining clusters appears to eliminate ageas the sole second parameter determining HB morphology in the case of constantmass loss between RGB and HB. We are unable to chose between the two competingvalues for M5's (absolute) metallicity: [Fe/H] = -1.40 (Zinn & West 1984) and-1.17 (Sneden et al. 1992). This level of discrepancy has a signifcant effecton the derivation of the distance modulus and absolute age of M5. Fromtheoretical isochrones and luminosity functions, we find an absolute age for M5of 13.5 \pm 1 Gyr (internal error, assuming perfect models and no [M/H] error)for the Zinn & West abundance scale and 11 \pm 1 Gyr for the higher abundancevalue.

CCD Photometry of the Globular Cluster M5. I. The Color-Magnitude Diagram and Luminosity Functions