This paper gives an overview of the European ACTS project AC329-ACTUAL (Application and Control of Widely Tunable Lasers in HD WDM Networks). This project was carried out during 1998 and 1999. The stated main objective of the project was: To use the state-of-the-art technology on widely tunable lasers available within the Consortium, to bring this to full maturity on a subsystem level and to demonstrate that wavelength agile transmitters based on widely tunable lasers can open the way to the next generation WDM and wavelength switching systems. This paper will give a description of the results From the project.