This is the final report on a study of laser-based intersatellite communications links. Three links are considered: between geostationary satellites, between geostationary and inclined geosynchronous satellites, and between geostationary and low earth orbit satellites. Section 1 provides historical & technical background on laser communications systems and an outline of ongoing optical intersatellite link (ISL) development programs. Section 2 analyzes the operational parameters of the three links under study. Section 3 reviews optical ISL technology and the current or projected performance of ISL components. Link gains & losses are identified in section 4 for both direct detection & heterodyne receivers and for direct modulation laser diodes & externally modulated gas & solid state lasers. Section 5 discusses the acquisition & tracking functions that are essential before data transmission can begin. Section 6 presents the conceptual design for the baseline direct detection system operating at 100 megabytes per second and for two options at one gigabyte per second. Performance parameters are listed for the baseline system with changes indicated for the two optional systems. A telescope is selected and the optical bench dimensions are established for all three systems. An outline is presented for the electrical system which supports the communications signal and controls the system for acquisition & tracking. The final sections review Canadian capabilities in optical ISL and outline a roadmap to achieve a Canadian presence in the optical ISL market.