Photoelectric photometry, covering a spectral regionfrom X=. 36 ii to 3* 4-u* is obtained for a large sample ofearly-type stars in the I Orion association with the photo� metric telescopes of the Lunar and Planetary Laboratory ofthe University of Arizona. The observations are interpretedin terms of the interstellar extinction phenomenon. Thecolor excesses of the stars are calculated from the observed (reddened) and intrinsic (unreddened) color indices. Nor� malized curves revealing the wavelength dependence of theextinction are then computed. Because of the low reddeninrin many parts of the association, the errors of the extinc� tion curves are often large. For this reason, regional meanextinction laws are determined from the data of individualstars in localized areas. A method that eliminates the useof filter effective wavelengths is then employed to obtainthe corresponding monochromatic extinction laws.