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abstract: |
    The specific frequencies of globular cluster systems, $S_N\propto {\cal N}_
    {\rm tot}/L_{V,{\rm gal}}\propto M_{\rm gcs}/M_{\rm stars}$, are discussed in terms of their connection to the efficiency of globular cluster formation in galaxy halos, which is claimed to reflect a generic aspect of the star formation process as it operates even at the current epoch. It is demonstrated that the total [*masses*]{} of GCSs are little affected by the dynamical destruction of low-mass clusters at small galactocentric radii. This permits direct, empirical estimates of the cluster formation efficiency by mass, $\epsilon_{\rm cl}\equiv M_{\rm gcs}^{\rm init}/M_{\rm gas}^{\rm init}$, even after $10^{10}$ years of GCS evolution. However, the standard practice of using only the stellar luminosities of galaxies as indicators of their initial total gas masses (and thus relating $S_N$ to $\epsilon_{\rm cl}$ in one step) leads to serious conceptual problems, that are reviewed here. The [*first specific frequency problem*]{}, which is the well known tendency for many brightest cluster galaxies to have higher than average $S_N$, is a global one; the [*second specific frequency problem*]{} is a local one, in which the more extended spatial distribution of GCSs relative to halo stars in some (not all) bright ellipticals leads 