agreement with previous RXTE timing data. In addition, the near-UV variability was found to lag by 1-2 seconds behind the X-ray variations, as would be expected from light echoes in a system with $P_{\rm orb} =4.1$ hr. Hynes et al. (2000b), combining data from HST, EUVE, UKIRT and RXTE, find that the IR to UV data suggests emission from both an optically-thick disk and another, flat spectrum component (possibly synchrotron), while the EUVE and X-ray data suggest a power law emission typical of a Galactic X-ray binary in a low-hard state. They conclude that XTE J1118+480, rather than experiencing a full outburst [ approaching the Eddington luminosity]{}, seems to be in a mini-outburst state [ (but see Kuulkers 2000)]{}.

In this paper, we describe the results of our optical spectroscopic campaign to monitor the evolution of XTE J1118+480 during its recent outburst (and early decline). In §2, we describe our observations and the data reduction techniques used. Our results concerning the continuum and line emission, a partial S-wave pattern and the interstellar absorption to the source are presented in §3 and discussed in the context of the current knowledge on XTE J1118+480 in §4. Our main conclusions are summarized in 