Are today's young people really more narcissistic?

A comment by Trzesniewski et al. on the idea that today's young people have inflated impressions of themselves compared with previous generations. They:

..investigated secular trends in narcissism and self-enhancement over the past three decades. Despite recent claims about the impact of the "self-esteem movement" on the current generation of young people, we found no evidence that college students' scores on the Narcissistic Personality Inventory increased from the 1980s through 2007 (N = 26,867), although we did find small changes in specific facets of narcissism. Similarly, we found no evidence that high school students' level of self-enhancement, defined by the discrepancy between their perceived intelligence and their actual academic achievements, increased from 1976 to 2006 (N = 410,527). These results cast doubt on the belief that today's young people have increasingly inflated impressions of themselves compared with previous generations.