The objective of the presentation is to expand the foundations of input into policy decision making relying on health technology assessments (HTA). HTAs are primarily based on systematic reviews (SR) and thereby mostly on randomized controlled trials (RCT). RCTs can be distinguished on a continuum between explanatory and pragmatic trials according to their level of control over variables in the study besides the examined technology. In explanatory trials emphasis are placed on internal validity in order to test the efficacy of a technology under ideal conditions while pragmatic trials emphasizes external validity and the effectiveness of a technology in normal daily practice. SR and HTAs favors internal valid trials and thereby proofs of possible cause-effect relationship between a technology and outcomes but at the expense of the wider perspectives of a technology. HTA have a policy-oriented perspective and aims at supporting health policy makers and therefore have to reflect policy applicable questions and answers. Simply relying on strictly controlled explanatory RCTs alone is too narrow to answer questions of relevance for policy making. It is suggested to supplement these highly controlled explanatory RCTs with the broader and more generalizable randomized pragmatic trials. Implications: HTAs incorporating both explanatory and pragmatic RCTs will depict both clinically efficacy measures and outcome measures pertinent for the patients reflecting a wider spectrum of outcomes for the overall performance of a technology. They will also demonstrate the natural variations in implementation of the technology in different settings and contexts including variations between users of the technology and for the groups of real-life patients. In general, including both explanatory and pragmatic RCTs in HTA gives one the possibility of answering not only the question Can it work? but also the question Does it work?