Pictures of gravitational lensing -- Determination of cosmological parameters by the gravitational lens effect -- Cosmic gravitational diagnostics -- Gravitational redshifts and lensing by large scale structures -- What the present observed lens systems tell about the lensing agent -- Gravitational lens models with elliptical geometry -- Amplification near a gravitational lens macro-caustic -- Statistics of lensing on extended sources -- Observational aspects of gravitational lensing -- Quasar-galaxy associations -- A search for gravitational lensing among highly luminous quasars : observational strategy and survey -- A search for gravitational lensing among highly luminous quasars: new results -- Gravitational magnification effects on distant 3CR galaxies -- 0957+561: The time delay revisited -- The time delay of Q0957-+-561 A,B from 10 years of optical monitoring -- Application of image processing techniques in a search for gravitational lenses and quasar pairs -- A search for gravitational lenses and quasar pairs and the discovery of a new multiple QSO system -- Evolution and gravitational lensing in quasar absorption line systems -- Preliminary analysis of high-resolution spectra for UM 673 A & B -- Bidimensional spectrography of the "clover leaf" H1413+117 at sub-arcsec. Spatial resolution -- The MIT search program for gravitational lenses -- First epoch VLBI observations of the gravitational lens system 2016+112 -- X-ray observations of gravitational lenses -- Consequences of gravitational lensing for gamma radiation from 3C273 -- Searching for cosmic strings (A la recherche des cordes perdues) -- Microlensing -- Microlensing calculations with a hierarchical tree code: New results -- Statistical investigations of the amplification near gravitational lens caustics -- The deconvolution of the quasar structure from the lightcurve of a high amplification event with the regularisation method -- The Hamburg quasar monitoring program at Calar Alto: Analyses of micro-lensing variability -- Photometric monitoring of 2237+0305 -- Spectrophotometry of 0957+561 and the micro-lensing effect -- IR imaging and the light curve of 2237+030 -- Clusters of galaxies: A new observable class of gravitational lenses -- Lensing the background population of galaxies -- The redshift distribution of faint galaxies - Implications for gravitational lensing -- The theory and practice of radio ring lenses -- Lens and source models for ARCS in cluster Abell 370 and Cl 2244 -- Modeling the giant arcs in A370 and A2390 -- New results from the gravitational telescope -- Probing rich galaxy clusters with mini-arcs -- Gravitationally lensed arcs as galaxy redshift indicators -- Spatial correlation in gravitationally lensed images -- Optical-infrared studies of arcs in Abell 370 -- Spectroscopy of arcs in Cl2244-02 and A370 (A5) -- First results on the spectroscopy of the arc-like object in Abell 2390 -- Deep photometry of C1.2244-02 in U colour with an electronographic camera -- Concluding remarks -- Gravitational lens candidates.