Preparatory steps for the experimental investigation of the highly forbidden 5s - 6s transition in rubidium using an atom trap and laser cooling are reported. A magneto-optical trap (MOT) has been assembled including saturation spectroscopy and a dichroic vapor laser lock. A frequency-doubled diode laser system has been installed to perform the spectroscopy of the forbidden transition with cold Rb atoms in the trap. The properties of the ns - n's transition in the presence of an external electric field have been investigated theoretically. A first measurement will be exploring the Stark-induced transition amplitude and the very faint magnetic dipole amplitude. The rubidium experiment is a precursor study for a long-term project at TRIUMF, Canada's National Laboratory for nuclear and particle physics, to measure atomic parity violation in the equivalent 7s - 8s transition in francium, the heaviest alkali atom which has no stable isotopes.