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The do-calculus was developed in 1995 to facilitate theidentification of causal effects in non-parametric mod-els. The completeness proofs of [Huang and Valtorta,2006] and [Shpitser and Pearl, 2006] and the graphi-cal criteria of [Tian and Shpitser, 2010] have laid thisidentification problem to rest. Recent explorations un-veil the usefulness of the do-calculus in three addi-tional areas: mediation analysis [Pearl, 2012], trans-portability [Pearl and Bareinboim, 2011] and meta-synthesis. Meta-synthesis (freshly coined) is the taskof fusing empirical results from several diverse stud-ies, conducted on heterogeneous populations and un-der different conditions, so as to synthesize an esti-mate of a causal relation in some target environment,potentially different from those under study. The talksurveys these results with emphasis on the challengesposed by meta-synthesis. For background material,see 〈http://bayes.cs.ucla.edu/csl papers.html〉.