We investigate irradiation-driven mass transfer in cataclysmic variables in the presence of shielding of the radiation by an accretion disk. We have shown that the shielding can cause a temporal drop of 3–5 magnitudes in the brightness of systems with orbital periods shorter than about 4 hr. This provides a possible explanation for the brightness variations in the VY Scl stars.

The classification scheme for Magnetic Cataclysmic Variables (MCVs) is addressed. When only ten or twenty MCVs had been discovered their classification was simple and based on direct observational properties. Now that the number of MCVs exceeds one hundred, the method of classification needs updating. One important consideration is the possibility that binaries might physically change their classification. For example will intermediate polars become polars as they evolve to shorter orbital periods? Or does a polar become an intermediate polar when synchronism is broken due to a nova?

I present preliminary results from the: VLT+FORS2 time resolved spectroscopy of the newly discovered cataclysmic variable (CV) Hα0242-28.

I present the key results of extensive optical spectroscopy obtained during the first three weeks of the 2001 super-outburst of WZ Sge. A sequence of Doppler maps of the accretion flow in various lines was constructed, and used to create real-time movies of WZ Sge as it evolved through the outburst. Main results include the detection of two-armed spiral asymmetries in the disk, emission from the irradiated donor star and an extended stream of emission around day 19 of the outburst that bears the hallmarks of a mass-transfer burst event.

We present an analysis of Rapid Keck Spectroscopy of the CVs AM Her (polar) and SS Cyg (dwarf nova). We decompose the spectra into constant and variable components and identify different types of variability in AM Her with different characteristic timescales. The variable flickering component of the accretion disc flux md the observational characteristics of a small flare in SS Cyg are isolated.

I present, brief status reports on three large observational projects that are designed to test our current understanding of the evolution of cataclysmic variables (CVs): The spectroscopic selection of new CVs in the Hamburg Quasar Survey, the search for pre-CVs based on Sloan colours and UK Schmidt/6dF multiobject spectroscopy, and the identification of CVs that descended from supersoft X-ray binaries using a HST/STIS far-ultraviolet spectroscopic survey.

A simple model of the boundary layer and accretion disk wind of dwarf novae in outburst is briefly described and applied to the Chandra Low Energy Transmission Grating spectra of WZ Sge and SS Cyg in outburst.