Observer metamerism has long been known to be an issue of concern, for color engineers. With the advent and mass proliferation of narrow-band display devices, this article addresses the issue of observer metamerisrn and puts it it? the context of fast understanding the implication of interobserver variations in the color matching functions (CMFs) and additionally designing the ideal set of primary illuminant spectral power distributions (SPDs) such that observer metamerism is minimized. The article also suggests the use of the Full Width Half Maximum (FWHM) and the number of modes (peaks) in the primary SPDs as a means of assessing the susceptibility to observer-to-observer variations between various modern display technologies. (C) 2009 Wiley Periodicals, Inc. Col Res Appl, 34, 391-398, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.20523