The use of near-infrared (NIR) measurements of photon migration has been recently demonstrated for the detection of breast cancer in Europe. Yet the clinical success of this potential screening tool depends upon consistent detection of the disease at earlier stages than is currently possible with conventional x-ray mammography. In this paper, we present the optical property measurements of 115 histologically classified breast tissue specimens in order to determine whether consistent and significant optical contrast exists for detection of the disease. Our in vitro optical properties measured with a double integrating sphere technique show consistent changes (yet statistically insignificant) in effective scattering coefficients, ms8, with tissue classification of infiltrating carcinoma (n=48), ductal carcinoma in situ (n=5), mucinous carcinoma (n=3), normal fatty (n=23), and normal fibrous tissues (n=35). However, there is little change in the in vitro tissue absorption coefficient, ma , measured at 749, 789, and 836 nm. For normal and diseased tissue specimens extracted from the same patient, we found differences in optical properties, indicating optical contrast. Using a finite-element prediction of light propagation, we evaluated this optical contrast for photon migration detection of ductal carcinoma in situ tissues using these optical properties measured in vitro.