Multiwavelength analysis of active star forming regions: The case of NGC 604

We analyse the integrated ultraviolet and optical spectra of the active star forming region NGC 604. The ultraviolet resonance wind stellar lines, the nebular optical emission lines and the higher order terms of the Balmer series and HeI absorption lines detected are interpreted using evolutionary models optimized for young star forming regions. The evolutionary state and the massive stellar content of the region is derived in a self-consistent way.