Book excerpt: This book constitutes the thoroughly refereed papers of the workshops held at the 9th International Conference on New Trends in Model and Data Engineering, MEDI 2019, in Toulouse, France, in October 2019. The 12 full and the three short workshop papers presented together with one invited paper were carefully reviewed and selected from 35 submissions. The papers are organized according to the 3 workshops: Workshop on Modeling, Verification and Testing of Dependable Critical systems, DETECT 2019, Workshop on Data Science for Social Good in Africa, DSSGA 2019, and Workshop on Security and Privacy in Models and Data, TRIDENT 2019.