This book constitutes the thoroughly refereedpost-workshop proceedings of the Second International Workshop on HybridSystems Biology, HSB 2013, held as part of the ECAL 2013 event, in Taormina,Italy, in September 2013; and the Third International Workshop on HybridSystems Biology, HSB 2014, held as part of CAV 2014, in Vienna, Austria, inJuly 2014.This volume presents 8 full papers together with 2invited tutorials/surveys from 21 submissions.The HSB 2013 workshop aims at collecting scientistsworking in the area of hybrid modeling applied to systems biology, in order todiscuss about current achieved goals, current challenges and future possibledevelopments.The scope of the HSB 2014 workshop is the general areaof dynamical models in biology with an emphasis on hybrid approaches, which arenot restricted to a narrow class of mathematical models, and which takeadvantage of techniques developed separately in different sub-fields.<
