Head-mounted projective displays (HMPD) have been recently proposed as an alternative to conventional eyepiece-type head-mounted displays (HMDs). HMPDs consist of a pair of miniature projection lenses, beamsplitters, and displays mounted on the helmet and retro-reflective sheeting materials placed strategically in the environment. The HMPD technology is first reviewed briefly, which includes its features and capabilities and a comparison with conventional visualization techniques, as well as our recent implementation of a compact HMPD prototype. Then we present some preliminary findings on retro-reflective materials and discuss a framework for collaborative AR environments, which supports at least three modes of collaboration: interactive local collaboration in an AR environment, passive distant collaboration, and interactive distant collaboration. Finally, two preliminary application examples of the HMPD technology for interactive collaboration in augmented environments are included, which demonstrate some of the HMPD characteristics and embody the framework for distant collaboration.