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We present 84 spectra of Type Ib/c and Type IIb supernovae (SNe), describingthe individual SNe in detail. The relative depths of the helium absorptionlines in the spectra of the SNe Ib appear to provide a measurement of thetemporal evolution of the SN, with He I 5876 and He I 7065 growing in strengthrelative to He I 6678 over time. Light curves for three of the SNe Ib provide asequence for correlating the helium-line strengths. We find that some SNe Icshow evidence for weak helium absorption, but most do not. Aside from thepresence or absence of the helium lines, there are other spectroscopicdifferences between SNe Ib and SNe Ic. On average, the O I 7774 line isstronger in SNe Ic than in SNe Ib. In addition, the SNe Ic have distinctlybroader emission lines at late times, indicating either a consistently largerexplosion energy and/or lower envelope mass for SNe Ic than for SNe Ib. WhileSNe Ib appear to be basically homogeneous, the SNe Ic are quite heterogeneousin their spectroscopic characteristics. Three SNe Ic that may have beenassociated with gamma-ray bursts are also discussed; two of these have clearlypeculiar spectra, while the third seems fairly typical.Comment: Accepted for publication in the March issue of AJ. 75 pages, 35  figures, 6 tables included as figures, AASTeX V5.

Optical Spectroscopy of Type I[CLC]b[/CLC]/[CLC]c[/CLC] Supernovae