The ages of SSCs span a wide range from as young as a few Myr to as much as several hundred Myr. In the case of the UV knots seen in W-R galaxies, the presence of W-R stars constrains the ages to be 3-8 Myr (Meynet 1995). In some cases, the young ages have been independently confirmed by spectral-synthesis modeling of the UV spectrum (Conti et al. 1996; Leitherer et al. 1996).
The ages for the bulk of SSCs, however, have been derived from broad-band optical colors. Ages from this method, unfortunately, are notoriously difficult to interpret, since the broad-band colors also depend on metallicity and reddening. From the narrow range of colors and the apparent absence of a ``fading vector'' in the distribution of V magnitude versus V - R color, Holtzman et al. (1992) argued that the SSCs in NGC 1275 have a relatively small spread in ages, perhaps between 10 to 300 Myr. It has subsequently been shown by Faber (1993), however, that the Holtzman et al. images were not sufficiently deep to allow this test to be performed unambiguously. Faber's simulations, in fact, cannot rule out cluster ages as large as 1 to 5 Gyr. The age determinations for the clusters in NGC 7252 (30-500 Myr; Whitmore et al. 1993) and the Antennae (4-40 Myr; Whitmore & Schweizer 1995) suffer from similar ambiguity, since they are also based on photometric properties.
In principle, spectroscopic data can furnish more reliable age estimates, but, thus far, attempts to derive ages from optical spectra have not yielded superior results compared to those based on photometric methods. Schweizer & Seitzer (1993) obtained spectra of the two brightest clusters in NGC 7252 and showed that the integrated light comes predominantly from late-A to mid-F stars. But beyond this broad statement, no definitive conclusion could be drawn, since the spectral indices in the blue-red region were of limited use for dating the clusters. The Mgb and Fe I 5270 features, for example, give degenerate values of the age, while the Balmer absorption lines, in addition to being discrepant with model predictions for unknown reasons, can be fitted with a large range of ages spanning almost a factor of 100. Zepf et al. (1995) performed essentially the same analysis for the the brightest cluster in NGC 1275.