Nurse clinicians make hundreds of small decisions every hour based on training, experience, and logical problem solving. Experience-based knowledge develops as they begin noticing cause-and-effect relationships and form personal theories that make them highly attentive to some factors and suspicious about others. The expert clinician uses these heightened clues about relationships to predict and avoid problems. Quantitative research provides the clinician with other information, gathered in a far more formal way, using sensitive measurements and controls to account for factors that have competing influence. This article offers pointers and a roadmap for reading and interpreting the formalized language, structure, and outcomes of quantitative research reports, with emphasis on issues of validity that affect a study’s strength for evidence-based practice decisions.