It is well known that atmospheric turbulence diminishes the performance of laser communications systems. Among the multiple degradations caused by turbulence is fading and surging of the received signal, usually referred to as scintillation. If a minimum probability of error receiver is employed for on-off keying (OOK), it is necessary to understand the two conditional probability densities (pdfs) corresponding to the transmission of ones and zeros. These probability densities are the distributions of signals received when the laser is on when sending binary ones and when the laser is off sending binary zeros. Many theoretical studies have determined the expected forms of the pdfs. An ongoing experimental study operating a low-power, low data rate link over a range of 9.3 Km has been started at Colorado State University-Pueblo to carefully examine the effects of atmospheric turbulence on laser communications. Experimental models of actual, true and typical pdfs have been obtained. The results do not always match theoretical predictions. The non-stationary nature of these pdfs is also a problem that must be addressed. This paper summarizes the experimental testing and shares a number of its conclusions.© (2006) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.