This investigation compared the speech naturalness ratings of perceptually fluent speech samples produced by nonstutterers and stutterers who had been treated in six different therapy programs. The treated stutterers were then divided into two groups based on ease of identification using stutterer/nonstutterers judgments. The fluent speech of one group of stutterers was easily recognized as being produced by stutterers. The second group produced fluent speech that was difficult to distinguish from that used by normal talkers. Finally, pretreatment severity ratings (i.e., mild, moderate, and severe) were compared with posttreatment naturalness scores. Results indicated that a statistically significant difference existed between the naturalness ratings of the nonstutterers and the treated stutterers. Also, a significant difference was found between the naturalness ratings of the easy-to-identify stutterers. Finally, no difference was found in the posttreatment naturalness ratings of stutterers rated as mild, moderate, and severe before treatment.