These proceedings summarize our present knowledge on astronomical molecules, highlight major problems to be addressed, and finally propose future work. Their theoretical understanding involves physics, numerical simulations and chemistry.

"The phenomena observed in young stellar objects (YSO), circumstellar regions and extra-galactic nuclei show some similarity in their morphology, dynamical and physical processes, though they may differ in scale and energy.

Young Stellar Objects (YSO) Evolution.- Outflow, Infall, and Rotation in High-Mass Star Forming Regions.- MERLIN and Puschino Observations of H2O Masers in Outer Galactic SFR S128N.- Observing Magnetic Fields in Star-Forming Regions.- Evidence for Co-Propagation of 4765- and 1720-MHz OH Masers in Star-Forming Regions.- Magnetic Fields in Star-Forming Regions: Theoretical Aspects.- VLBI Water Maser Proper Motion Measurements in Star-Forming Regions.- High-Resolution Observations in B1-IRS: Ammonia, CCS and Water Masers.- The Kinematics, Physical Condition and Magnetic Field of the W3 IRS5 Region.- EVN Observations of H2O Masers Towards the High-Mass Young Stellar Object in AFGL 5142.- AGN/Starburst Evolution.- Gravitationally Induced Inflow in Starbursts and AGN.- Feeding Monsters - A Study of Active Galaxies.- The QSO Hosts I Zw 1 and 3C 48: Prototypes of a Merger-Driven Quasar Evolution?.- H20 Megamasers: Accretion Disks, Jet Interaction, Outflows or Massive Star Formation?.- Probing the Obscuring Medium Around Active Nuclei Using Masers: The Case of 3C 403.- Low-Luminosity Extra-Galactic H20 Masers.- Statistical Approach.- Monitoring Water Masers in Star-Forming Regions.- Dense Gas, Chemistry and Star Formation in Luminous Galaxies.- A Molecular Ring in the Liner NGC 5218.- Neutral Gas in Starbursts and Active Galactic Nuclei.- CO, 13CO, and [CI] in Galaxy Centers.- Diagnostics of YSO.- Chemical Evolution of Protostars.- Model of the W3(OH) Environment Based on Data for Both Maser and "Quasi-Thermal" Methanol Lines.- Long-Term Monitoring of 6.7- and 12.2-GHZ Methanol Masers.- Ultra-Compact H II Regions.- Maser Action in Methanol Transitions.- The Methanol Maser Emission in W51.- NGC7538 IRS1 N: Modeling a Circumstellar Maser Disk.- Diagnostics ofAGN/Starbursts.- Dense Molecular Gas Around Protostars and in Galactic Nuclei: PDRs and XDRs.- Molecular Absorption in Cen A on VLBI Scales.- High-Resolution Acta Observations of the Circumnuclear Molecular Clouds of NGC 4945.- Megamasers: Molecular Diagnostics of the Nuclear ISM.- Understanding Extragalactic Hydroxyl.- The Sub-PC Scale Accretion Disk of NGC 4258.- OH Megamasers: Circumnuclear Gas in Starbursts.- Continuum EVN and MERLIN Observations of Ultra Luminous Infrared Galaxies.- Molecular Gas in the Abell 262 Cluster Galaxy UGC 1347.- Dense Gas Diagnostics: Maser Excitation and Variability.- Spectral Line and Continuum Radiation Propagation in a Clumpy Medium.- A Thin Ring Model for the OH Megamaser in IIIZw35.