This experimental research describes sight translation by comparing it to simultaneous and consecutive interpreting. Since the beginning of interpreting research, sight translation has mostly been considered as a pedagogical exercise and interpreters are rarely trained in this task per se. However, sight translation, consecutive interpreting and simultaneous interpreting are performed under different conditions, and these determine how cognitive resources are managed and what strategies are adopted. The study compares the performance of six professional interpreters in sight translation, simultaneous interpreting and consecutive interpreting with a view to identifying particular constraints and problems. Results show that interpreters face different difficulties and use different efforts in each mode.