Key components of healthcare interventions include ‘active ingredients’ (intervention components that can be specifically linked to effects on outcomes such that, were they omitted, the intervention would be ineffective). These should be reported in titles and abstracts of published reports of randomized controlled trials (RCTs). However, reporting of non-pharmacologic interventions (NPIs), particularly behaviour change interventions (BCIs), is difficult, owing to their complexity. This illustrative review compares how pharmacologic interventions (PIs), NPIs and BCIs are specified in titles and abstracts to clarify how reporting of NPIs and BCIs can be improved. MEDLINE and Embase were searched for RCTs published in the British Medical Journal, The Journal of the American Medical Association, The New England Journal of Medicine, The Lancet and Annals of Behavioral Medicine from 2009 to March 2011. All types of intervention, participant and outcome were included. A random sample of 198 studies (sampled proportionally from included journals) stratified by intervention type (PI/NPI) was taken: 98 evaluated PIs, 96 evaluated NPIs and four evaluated both. Studies were coded for the presence or absence of key components. The frequency data were analyzed using the chi-square test. Active ingredients were named in 88% titles and 95% abstracts of PI reports, and in 51% titles and 71% abstracts of NPI reports, with a significant association between intervention type and reporting of active ingredients in titles (χ 2(1) = 28.90; P < 0.001) and abstracts (χ 2(1) = 16.94; P < 0.001). Active ingredients were named in BCI reports in 37% titles and 56% abstracts, and in other NPI reports in 66% titles and 86% abstracts. There was also a significant association between intervention type and reporting of active ingredients in titles (χ 2(1) = 6.68; P = 0.010) and abstracts (χ 2(1) = 8.66; P = 0.003). Reporting practices also differed for such components as the trial setting and intervention provider. This review highlights the need for improved reporting of NPIs (particularly BCIs) and indicates that a set of agreed labels and definitions for complex NPIs could facilitate standardized reporting. This would ensure that interventions can be faithfully replicated and that evidence for interventions can be appropriately synthesized.