The movements of individual crayfish, Orconectes virilis, were followed by hand captures of marked animals for over a year. Considerable variability was found in both the total home-range length recorded for individuals and in the capture-to-capture movement (both ranged from zero to 308 m). The average of the capture-to-capture movements was 33 m; the mode was 0-5 m (crayfish found in same grid area). Males and females did not differ in size of home-range or capture-to-capture movement, but several aspects of the data indicate that males moved more. Size was significantly correlated with movement for females but not males. Animals frequently moved farther after a molt, and many animals moved into shallow, sandy areas around the time of a molt.