The number of good‐quality intervention studies (randomized controlled trials) has more than doubled since the 2003 Cochrane Review (Law et al. 2003), and it is important to reflect on the conclusions that can be drawn from such reviews. Coupled with the work of the CATALISE consortium on developmental language disorders (DLD) (Bishop et al. 2017, 2017), this paper is timely. The broad conclusion in this paper is that speech and language therapists (SLTs) in the UK ought to confine their activity to what they are perceived to be ‘best at’, their so‐called unique selling point, which the authors see as individualized interventions with the children with the most severe problems and let others take responsibility for the rest. The analysis is, like that in most clinical guidelines, both wide ranging and rather selective based on a curious hybrid of single papers and both narrative and systematic reviews. The problem is both that the intervention evidence is a bit patchy and that lack of evidence should never be confused with negative evidence.