Construction has begun on ISAC, a radioactive ion beam (RIB) and accelerator facility that utilizes the ISOL (on-line isotope separation) production method. A five-year budget for this new radioactive beam facility at TRIUMF was approved in June 1995. ISAC includes: a new building with 5000 m2of floor space, a beam line with adequate shielding to transport up to 100 &mgr;A of 500 MeV protons from the TRIUMF cyclotron to two target/ion-source stations, remote handling facilities for the targets, a high-resolution mass-separator, linear accelerators and experimental facilities. The ISAC target/ion source station permits the production of nuclei far from stability over a large isotopic range with high luminosity. Ions from the target/ion-source will be transported at energies up to 60 keV through a low-resolution pre-separator magnet followed by a high-acceptance, high-resolution mass-separator magnet to a variety of low energy experimental stations. Alternatively, ions withq/A⩾1/30and an energy of 2 keV/amu can be bunched in the low energy beam transport line prior to a RFQ accelerator. The final energy will be variable from 0.15 to 1.5 MeV/amu. The accelerated beams will be used primarily for nuclear astrophysics studies. The buildings are now complete and the commissioning of the target/ion source, mass separator and RFQ systems has started. The TRIUMF neutral atom trap (TRINAT) is scheduled to begin using the low energy ISAC beam in November 1998. The full energy beam will become available for the DRAGON recoil spectrometer at the end of 2000. A new five-year plan will be presented to the Canadian Government before the end of 1998. The plan includes an upgrade of ISAC to permit acceleration of the RIB up to 6.5 MeV/amu for masses up to 150. ©1999 American Institute of Physics.