As a leading member of the Social Democratic Party of Switzerland he opposed the First World War. Grimm was the main organiser of the Zimmerwald Movement and the chairman of the International Socialist Commission in Berne 1915 – 1917. After the Grimm–Hoffmann Affair he had to resign from this function.
Grimm was among the founders of the 2½ International. He held various parliamentary seats and executive functions from communal to federal level between 1909–1955. In 1946 he became President of the Swiss National Council.
- Media related to Robert Grimm at Wikimedia Commons
- Grimm, Robert in German, French and Italian in the online Historical Dictionary of Switzerland.
- Robert Grimm Papers in the International Institute of Social History
| President of the National Council