This book collects the revised selected proceedings of the  First International Symposium in Molecular Logic and Computational Synthetic Biology ( MLCSB), held in Chile, Santiago, in  December 2018. The volume contains 7 full revised papers along with 2 surveys from 19 submissions presented at the symposium. One of the goals of the MLCSB 2018 was to explore the potential of molecular logic frameworks to study the emerging behavioural patterns in biological networks, combining discrete, continuous and stochastic features, and resorting both to specific or general-purpose analysis and verification techniques.