Dereddened UV spectra of 3C 279 binned in ~100 Å wide intervals. As for other synchrotron sources, the spectra steepen with decreasing intensity. However, at the lowest intensity the spectra are again flat, possibly due to the presence of steady accretion disk emission. Error bars are 1 σ uncertainties. Open symbols represent average IUE spectra for various typical flux levels (see Table 3): the "high" state spectrum (1998 July; circles) was obtained by coaddition, weighted with the exposure time, of spectra SWP 33864, 33865 for the 1230–2000 Å range and LWP 13566, 13567 for the 2000–3000 Å range; the "medium" state (1989 January–1992 May; squares) is the coaddition of SWP 35443, 36420, 42132, 40489, 44806 and LWP 14933, 15677, 20891, 19492, and 23207; the "low" state (1993 December and 1996 January; triangles) has been obtained by coadding SWP 49681, 49686, 56635 and LWP 31882, 31906, 31908, and 31914; the "very low" state (1993 January; diamonds) is the coaddition of SWP 46649, 46653, 46657, 46662 and LWP 24652, 24656, 24661, and 24665; stars represent the "extremely low" state observed in 1995 January (SWP 53261). Filled symbols represent HST FOS spectra in 1992 April (squares) and 1996 January (circles). Superimposed on each representative spectrum is the power‐law curve that best fits the data in the interval 1230–2700 Å. Spectral indices are ﹩\alpha =1.47\pm 0.02﹩ (1988 July), ﹩\alpha =1.70\pm 0.03﹩ (1989 January–1992 May), ﹩\alpha =1.92\pm 0.07﹩ (1993 December and 1996 January), ﹩\alpha =0.89\pm 0.15﹩ (1993 January), ﹩\alpha =1.65\pm 0.13﹩ (HST FOS 1992), and ﹩\alpha =2.25\pm 0.04﹩ (HST FOS 1996).