The past ten years has seen very significant advances in high resolution imaging arising from the construction and routine operation of Very Long Baseline Interferometer arrays in the US, Europe and Australia. Coupled with the launch of the first VLBI antennas into earth orbit, angular resolution below a milliarcsecond has been achieved on a large number of compact objects. Nevertheless, while the application of phase referencing to VLBI observations has increased the number of sources that can be imaged by VLBI, the astrophysical impact of interferometry on baselines greater than a few tens of km, has been severely limited by sensitivity. The next decade promises to bring about very significant increases in continuum sensitivity at high angular resolution through new developments in VLBI recording devices to achieve recording bandwidths of 4 to 8 Gbits per second, and by direct optical fibre-linked long baseline arrays. In the following decade, the Square Kilometre Array will herald a new era of high resolution radio astronomy with a factor of 100 sensitivity increase. In addition to vastly increasing the sample of non-thermal sources accessible to VLBI, the SKA will open up high angular resolution imaging to a new regime of astrophysics, by enabling milliarcsecond resolution imaging of thermal radio emission. At wavelengths of a few centimetres the SKA, in combination with next generation space VLBI missions, will allow direct imaging of the x-ray emitting accretion disks in galactic nuclei.