“Visualizing Data” is a four day course where participants are introduced to the theory and practice of data visualization. Visualization will be taught as a design process: In order to produce effective visualization one needs to have a clear communication purpose in mind, know the audience and the medium, understand visual perception and be able to use the tools of the trade. This broad range of skills requires the integration of theory and practice. Each lecture starts with an introduction to relevant theory followed by a guided ggplot2 practical.