With so much interest in the science of mindfulness and a proliferation of research, understanding the field can feel a little disorienting. We often hear about the results of a study, but it can be difficult to contextualize the 
findings in relation to the rest of mindfulness research.
Here, we’re not trying to review the state of mindfulness research. That’s a book-length project, and others have done it well (see Brown, Creswell & Ryan, 2015). Instead, we outline three distinct types of mindfulness research that are being pursued – definition, efficacy, and mechanisms – and place them within a coherent whole. We hope this provides a context to interpret the exciting scientific findings that are now consistently emerging.
1. Definition & Measurement
First, in order to study something scientifically, we need an operational definition of the construct. The question, “What is mindfulness?” is more complicated than it sounds. It is an important question because if the definition is 
sloppy, then mindfulness is more difficult to measure accurately. If the measurement of mindfulness isn’t accurate, then it’s harder to assess its therapeutic potential. So, researchers have done ‘construct validation’ studies where they define mindfulness, design a way to measure it, and then examine how well their approach fares. Generally, researchers have sought to measure mindfulness through ‘self-report.’ This means that the research participant is asked questions regarding their level of mindfulness and they report on their own level of mindfulness. Measures such as the Mindful Attention Awareness Scale and the Five Facet Mindfulness Questionnaire have been influential in the field.
However, some scientists have highlighted the limitations of self-report measures. People may be biased in their report and, reporting on one’s level of mindfulness seems to presuppose a modicum of mindfulness itself. That is, before we develop mindfulness, it is difficult to accurately report on the activities of our mind. Thus, other researchers have attempted to develop alternative ways of assessing mindfulness, such as attention performance-based approaches. Although measurement studies tend not to receive attention in the mindfulness press, they exert an important impact on the direction of the field.
2. Efficacy
Ultimately, the value of mindfulness is its ability to positively impact our lives. This is a question of the efficacy of mindfulness. Ok, but mindfulness is efficacious for what? There are three broad classes of people (whether adult 
or youth) for which mindfulness might be helpful. The first is people with clinical diagnoses. This includes those with psychiatric or medical conditions where mindfulness might improve the symptoms or make those symptoms more tolerable. Next, mindfulness might be applied to ‘healthy’ but stressed groups. These people do not have a medical or psychiatric diagnosis, but experience stress that compromises their well-being. Third, mindfulness may have a role in potentiating the well-being of populations who do not experience elevated stress but are seeking more meaning and psychological flourishing. Because medical and psychiatric conditions create a substantial public health burden, the primary research interest in mindfulness has been on the first group. This is reasonable, however, it’s important to acknowledge that mindfulness may be an important tool for potentiating well-being, not only alleviating distress.
So, how is the efficacy of mindfulness for a given population assessed? The strongest form of evidence for the efficacy of a treatment is randomized clinical trials. The approach of the randomized clinical trial has been borrowed and adapted from medication-based trial designs. To sketch this very briefly, in clinical trials for candidate medications, a patient population is defined (adults with depression, for example) and then research participants are randomized to receive the antidepressant medication or a placebo pill. The patients don’t know if they’re receiving the antidepressant or the placebo, and the scientist evaluating the patients doesn’t know either. Patients are assessed for depression and the group getting antidepressants is compared with the group getting placebo pills.
In trials assessing a psychosocial ‘treatment’ like mindfulness – rather than a medication – it’s harder to determine what the equivalent of the placebo pill should be. If you test mindfulness against no treatment at all, mindfulness almost always wins – but this is not a strong demonstration of the efficacy of mindfulness. Now, researchers are using more rigorous designs where mindfulness is tested against another bona fide treatment or against an ‘active control’ which features everything about mindfulness treatment that might be helpful – social support, a caring teacher, the therapeutic environment – except the mindfulness itself. This is an attempt to isolate the impact of mindfulness and assess its role in clinical improvements. The efficacy of mindfulness has been reported in several recent meta-analyses that aggregate the findings from multiple studies. The efficacy of mindfulness has been primarily tested among adults, although there is growing research interest in assessing mindfulness for youth.
3. Mechanisms of Mindfulness
Evidence for the efficacy of mindfulness is important, but leaves an important question unanswered: how does mindfulness work? This is not merely a theoretical question. When we can understand how something works, it 
gives more control to distill the “active ingredients” and may highlight ways to make the treatment more powerful. How does mindfulness ‘get under the skin’? This question can be answered at different levels of analysis. We can talk about the psychological mechanisms through which mindfulness promotes well-being. For example, researchers have emphasized the ways in which mindfulness reduces avoidant styles of coping, which are associated with distress and mental health symptoms. It is assumed that any psychological process has neurobiological correlates. That is, when we observe psychological change, we should expect there to be accompanying neurobiological change. Scientists have conducted hundreds of studies assessing the impact of meditative practice on the structure and function of the brain. Researchers are digging into more basic biological levels of analysis. For example, scientists are seeking to understand how meditation practice might impact basic cellular functioning. More recently, a group of behavioral geneticists examined the ‘heritability’ of mindfulness – the way that genes impacts our level of mindfulness. These data help enrich our understanding of the mechanisms of mindfulness.
3. Conclusion
The three lines of research – measurement, efficacy, mechanisms – are beginning to form a more mature integrated understanding of mindfulness and associated meditative practices. We hope that this framework helps you contextualize and interpret scientific findings regarding mindfulness.
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