Between 600 and 1300 nm the optical absorption coefficient pa of mammalian soft tissues is quite low', ranging from about 0.1 - 1.0 cml. The scattering coefficient ps, on the other hand, is high - typically 100 - 1000 cm'. This scattering is forward peaked, so that g, the mean cosine of the scattering angle, is about 0.9. Since the net result of several small angle scattering events is similar to that of a single isotropic scatter, it is useful to define a reduced or transport scattering coefficient p. = (1-g) Ns. Even this reduced coefficient, which is usually 5 - 50 cm', is typically 10 -100 times the absorption coefficient.