This project regards an **introductory course to open science** launched in May 2022 at Erasmus MC, **aimed at PhD students in the biomedical sciences**. We cover the **what, why, how, and when of open science** in a **two-day interactive course**, aimed at **small groups of students** (10-25 people). - **what** **of open science**: definition of open science and its principles - **why** **of open science**: history of science and its interplay with governmental and economic stakeholders and how loss or renewed trust in science determined the implementation of several criteria for success in academia (e.g., H-index), which then contributed to a reproducibility crisis - **how** **of open science** (largest section of the course): how to implement open science across different steps of the research cycle. 1) how to form more informative RQs and hypotheses, confirmatory/exploratory continuum, preregistrations & RR, 2) improving diversity in your studies, 3) analysing your data in a reproducible manner with RMarkdown and sharing your project openly with OSF, 4) questionable research practices and transparent reporting. - **when** of open science: we encourage participants to think critically about open science and how it should be a *means* to improve their research, rather than an end goal. We also examine tangible benefits and costs of open science and how to address its challenges