At the end of 2025, WSL's 647 employment contracts amounted to 564,4 full-time equivalents (FTEs). Scientists accounted for roughly 58.1 % of all staff (FTEs). The scientific staff includes 81 doctoral students and 54 post-doctoral researchers. Its staff also included 16 apprentices.
The proportion of women (excluding apprentices) was approximately 42,8 %. Foreign staff accounted for nearly 37,4 %. WSL staff came from 40 countries. German was the mother tongue of most employees (73,3 %).
WSL launched a Visiting Fellows programme to increase research collaboration with foreign scientists. The aim of this programme is to enable leading international researchers at an advanced stage of their career to spend 3-12 months conducting research at WSL. Fellowships are awarded annually to international applicants.