Lehigh benefits from a very good student-teacher ratio, has a good endowment, and SAT scores that have been inching up in recent years. SAT scores will likely come and go, but the student-teacher ratio is probably one of Lehigh's biggest long-term advantages. Lehigh is private and small -- in terms of size, it probably has more in common with Liberal Arts Colleges like Mt. Holyoke or Lafayette, than with the giants it is currently compared to, like Penn State, Rutgers, Indiana, and UIUC. Lehigh gets put on the main list with those big "Research I" universities because it offers a number of Ph.D. programs (including one in English). There's still a bit of a grey zone: I'm not sure why Lehigh is counted as a research university while schools like Bucknell or Colgate (both technically "universities") are counted as LACs.
Another question comes up. Are we really better than:
41. Georgia Institute of Technology *
42. University of California – Davis *
43. Tulane University (LA)
University of California – Irvine *
45. Univ. of California – Santa Barbara *
46. Rensselaer Polytechnic Inst. (NY)
University of Texas – Austin *
University of Washington *
Yeshiva University (NY)
50. Pennsylvania State U. – University Park *
University of Florida *
52. George Washington University (DC)
The answer is 'yes,' if you're looking for good student-teacher ratios, retention and graduation rates, and research money (mainly in the sciences and engineering). But, it might be arguable if you're looking for things that U.S. News isn't interested in, such as 1) the size of the library, 2) breadth of offerings, or 3) name-recognition. The one I pay most attention to is breadth of offerings, since that is the most easily remedied: you currently can't take Hindi at Lehigh, and Arabic is available -- at the beginner level only -- through a consortium program; the classics department is one person; there's no linguistics; and there's no dedicated art history major. All stuff that can be improved!