© The Author(s) 2012 Reprints and permission:

I am honored to have another opportunity to share my thoughts with readers of the issues of the 25th anniversary volume of Nursing Science Quarterly. In my first essay, I shared thoughts about nursing science and nursing sciencing (Fawcett, 2012). In this essay, I share thoughts about evi-dence-based nursing practice. The evidence needed for evidence-based nursing practice usually is regarded as the findings of empirical nursing research. Inasmuch as the purpose of research and other modes of inquiry is theory development (Kerlinger & Lee, 2000), I regard findings from all modes of inquiry as theories in the form of articulation of new theories and results of tests of existing theories. Although many of us tend to think about theories only as empirical entities, the diverse types of theo-ries that serve as evidence for nursing practice (see Table 1) are developed by means of both empirical and non-empirica