Educational research literature seems to highlight the use of different research methods, but there appear to be three main research strategies widely used and discussed. These are experiments, surveys and case studies. This paper concentrates on the experimental approach, which could be deemed for this paper to be of the “quantitative tradition”. The three strategies differ, then in two respects: (1) in how many cases are studied and, (2) in how these are selected. Strategies may be used to investigate any particular research topic, their strengths and weaknesses will have varying significance, depending on the purposes and circumstances of the research. The overall picture that emerges is that the experimental approach is based on multiple and varied sources of evidence and it must attend to process as well as to the outcome, it is better when it is theory-driven and it leads ultimately to multiple analyses that attempt to consolidate the program effect within some reasonable range. One theme that underlies the other research strategies namely, the case study and survey method, and that illustrate the increasing awareness of the tentativeness and frailty of the experimental approach concerns the importance of human judgement in research. Evidence bearing a causal relationship emerges and it is not a trivial matter to integrate or resolve conflicts and constraints.