The Shaped Pupil Coronagraph (SPC) is a high-contrast imaging system pioneered at Princeton for detection of extra-solar earthlike planets. It is designed to achieve 10-10 contrast at an inner working angle of 4λ/D. However, a critical requirement in attaining this contrast level in practice is the ability to control wavefront phase and amplitude aberrations to at least λ/104 in rms phase and 1/1000 rms amplitude, respectively. Furthermore, this has to be maintained over a large spectral band. The High Contrast Imaging Testbed (HCIT) at the Jet Propulsion Lab (JPL) is a state-of-the-art facility for studying high contrast imaging systems and fine wavefront control methods. It consists of a vacuum chamber containing a configurable coronagraph setup with a Xinetics deformable mirror. In this paper, we present the results of testing Princeton's SPC in JPL's HCIT. In particular, we present the achievement of 4x10-8 contrast using a speckle nulling algorithm, and demonstrate that this contrast is maintained across wavelengths of 785, 836nm, and for broadband light having 10% bandwidth around 800nm.© (2006) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.