In a recent blog post, Howard Aldrich argued that social scientists should drop the distinction between quantitative and qualitative research. I want to push back here and argue that there are important differences between the two methods which must be recognized to ensure high quality research. To be sure, the starting point of the discussion should be recognition of the underlying unity of research methodology, about which Charles Ragin has written eloquently. Quantitative and qualitative methods are both tools for advancing theory and knowledge. But these methods advance theory in distinct, complementary ways. To realize the full potential of research methodology requires recognizing these differences.