It is shown that sufficient progress in the design and manufacture of thin film interference filters has been made to consider the construction of filters with the rather complicated spectral characteristics necessary for the adjustment of the spectral response and spectral power distributions. By way of example, the calculated and experimental performance of filters for changing the color temperature of a light source and for duplicating the color mixture functions of the CIE standard observer are given. Other examples discussed are filters for obtaining a uniform spectral response of optical systems consisting of a light source and a monochromator, with or without a detector.