  By employing two different spectroscopic techniques we have mapped out the
variable ISM dust extinction endemic to globular cluster M4. We derive an
average E(B-V) reddening of 0.33 +/- 0.01 and R = 3.4 +/- 0.4, both in good
agreement with previous studies of M4. For individual stars in the most heavily
reddened regions of M4, we find E(B-V) values significantly higher than those
inferred by studies of interstellar gas; for heavily reddened regions, the gas
measured in column density measurements may not completely trace the dust.
