1 INTRODUCTION

2 OBSERVATIONAL DATA  
2.1 Gaia-ESO Survey spectroscopy  
2.2 Gaia DR2 astrometry  
2.3 Supporting data

3 MEMBERSHIP SELECTION  
3.1 Spectroscopic membership indicators  
3.2 Non-spectroscopic membership indicators  
3.3 Known high-mass members  
3.4 Combining membership information  
3.5 Final sample of members

4 KINEMATIC ANALYSIS  
4.1 Kinematic outliers  
4.2 Expansion and rotation  
4.3 Velocity gradients  
4.4 Velocity distribution of the entire population  
4.5 Velocity distribution of subgroups within the Lagoon Nebula  

5 DISCUSSION  
5.1 Current and past dynamical states  
5.2 Expansion of the Lagoon Nebula population  

6 SUMMARY