  Modern optical spectrographs and optical interferometers push the limits in
the spectral and spatial regime, providing important new tools for the
exploration of the universe. In this contribution I outline the complementary
nature of spectroscopic & interferometric observations and discuss different
strategies for combining such data. Most remarkable, the latest generation of
"spectro-interferometric" instruments combine the milliarcsecond angular
resolution achievable with interferometry with spectral capabilities, enabling
direct constraints on the distribution, density, kinematics, and ionization
structure of the gas component in protoplanetary disks. I will present some
selected studies from the field of star- & planet formation and hot star
research in order to illustrate these fundamentally new observational
opportunities.
