We present preliminary results of a simultaneous X-ray/optical campaign of the prototypical LMXB Sco X-1 at 1 10 Hz time resolution. Lightcurves of the high excitation Bowen/HeII emission lines and a red continuum at λc ˜ 6000 Å were obtained through narrow interference filters with ULTRACAM, and these were cross-correlated with simultaneous RXTE X-ray lightcurves. We find evidence for correlated variability, in particular when Sco X-1 enters the Flaring branch. The Bowen/HeII lightcurves lag the X-ray lightcurves with a light travel time which is consistent with reprocessing in the companion star while the continuum lightcurves have shorter delays consistent with reprocessing in the accretion disc.