Wide-field (~14' x 14') CCD photometry in V of a field centered on M87 = NGC 4486 is used to examine the spatial structure, luminosity function, and specific frequency of the galaxy's globular cluster system (GCS). The salient results are as follows: (1) As recently reported by McLaughlin et al., the radial profile of the GCS shows an excess component which coincides in position and size with the cD envelope of the galaxy's halo. (2) In projection, the GCS of M87 is definitely elliptical in shape, with a major axis position angle which roughly coincides with that of the galaxy isophotes. However, its ellipticity increases with galactocentric radius faster than does the ellipticity of the underlying halo light. (3) The luminosity function of the GCS is well described by a Gaussian of dispersion σ = 1.73, and peak magnitude V^0^ = 24.2. We confirm earlier claims that the bright half of the luminosity function shows no significant variation with galactocentric radius, out to R~6.8'. (4) We have computed the run of the ratio of globular cluster numbers to halo luminosity (specific frequency) over the region 1.2' <~ R <~9.1' we find that the net specific frequency of M87, for (m - M)_V_(Virgo) = 31.0 +/- 0.2, is S_N_ = 14 +/- 4, which is almost three times greater than for other, more normal Virgo ellipticals. A brief discussion of this high-S_N_ phenomenon is given, and we expand on the conclusion of McLaughlin et al. that the high S_N_ of the M87 cD envelope implies that this structure was accreted while still gaseous.