An international collaboration on the multiwavelength search for and studies of active galaxies between the Byurakan Astrophysical Observatory (Armenia) and Observatoire de Haute-Provence (France) has been ongoing since 1997. The blue stellar objects of the first Byurakan survey have been studied in order to reveal and build a sample of new bright quasistellar objects and to determine their surface density. On the basis of optical identifications of 1577 IRAS point sources, a new (Byurakan-IRAS galaxy) sample of IRAS galaxies has been constructed and studied. 90 bright Seyfert 1 galaxies have been observed with a high resolution to make a fine analysis of their emission line profiles and to study their emission line regions. A new programme of investigation of Roentgen Satellite (ROSAT) sources identified by the Hamburg quasar survey has been conducted to search for new narrow-line Seyfert 1 galaxies. Databases and observations in the optical, infrared, radio and X-ray ranges are being used.