On August 8, 2001, Melipal became the fourth Unit Telescope of ESO's VLT to start regular scientific operations. Accordingly, the Paranal Science Operations team is now providing support for execution of observation programmes of the astronomical community on all four individual 8 m telescopes of the VLT. The operational model developed and applied by this team is based on the concept that optimal exploitation of the unique potential of the VLT and of its instrumentation requires support by dedicated qualified and experienced astronomers. This applies to observing both in visitor mode and in service (queue) mode, between which VLT operations are shared approximately in a 50/50 proportion. The Paranal Science Operations team has been staffed to implement the above-mentioned operational concept in collaboration with a mountain-based engineering team for technical support, and with groups based at ESO's headquarters in Germany for front- and back-end contacts with the astronomical community. Together with these teams, and based on the experience acquired since the start of operations of the first UT in April 1999, operational procedures have been refined and new operational tools have been implemented. In this process, the aspects that are particularly revelant for on-site operations include the short-term scheduling of service mode operations, and the reporting and tracking of the service mode programme execution status.