Scripts and Scientific Workflow Management Systems (SWfMSs) are common approachesthat have been used to automate the execution flow of processes and data analysis in scien-tific (computational) experiments. Although widely used in many disciplines, scripts arehard to understand, adapt, reuse, and reproduce. For this reason, several solutions havebeen proposed to aid experiment reproducibility for script-based environments. However,they neither allow to fully document the experiment nor do they help when third partieswant to reuse just part of the code. SWfMSs, on the other hand, help documentationand reuse by supporting scientists in the design and execution of their experiments, whichare specified and run as interconnected (reusable) workflow components (a.k.a. buildingblocks). While workflows are better than scripts for understandability and reuse, they stillrequire additional documentation. During experiment design, scientists frequently createworkflow variants, e.g., by changing workflow components. Reuse and reproducibilityrequire understanding and tracking variant provenance, a time-consuming task. This the-sis aims to support reproducibility and reuse of computational experiments. To meetthese challenges, we address two research problems: (1) understanding a computationalexperiment, and (2) extending a computational experiment. Our work towards solvingthese problems led us to choose workflows and ontologies to answer both problems. Themain contributions of this thesis are thus: (i) to present the requirements for the con-version of script to reproducible research; (ii) to propose a methodology that guides thescientists through the process of conversion of script-based experiments into reproducibleworkflow research objects; (iii) to design and implement features for quality assessmentof computational experiments; (iv) to design and implement W2Share, a framework tosupport the conversion methodology, which exploits tools and standards that have beendeveloped by the scientific community to promote reuse and reproducibility; (v) to designand implement OntoSoft-VFF, a framework for capturing information about software andworkflow components to support scientists manage workflow exploration and evolution.Our work is showcased via use cases in Molecular Dynamics, Bioinformatics and WeatherForecasting