Muscle stiffness potentially contributes to joint stability from both mechanical and neuromuscular perspectives. The spinal stretch reflex (SSR) is a component of neuromuscular control which contributes to joint stability. It was hypothesized that higher triceps surae (TS) stiffness would correspond with shorter SSR latency and greater SSR amplitude in the soleus via enhancement of the mechanical coupling of the muscle spindle and the stretch stimulus. TS stiffness and the soleus H-reflex and SSR were assessed with subjects (20 males and 20 females) seated, and the soleus active to -15 %MVC. Stiffness was estimated from the damped frequency of oscillatory motion about the ankle in the sagittal plane. The H-reflex was elicited by electrically stimulating the tibial nerve, and the SSR was evoked via mechanical ankle dorsiflexion perturbation. Group differences in TS stiffness, H-reflex latency and amplitude, and SSR latency and amplitude were assessed via independent samples t-tests. Relationships between stiffness and SSR latency and amplitude, respectively, were assessed via bivariate correlational analyses. Structural and mechanical stiflfiiess were significantly greater in males (p<0.05). Therefore, reflex characteristics were compared across high (males) and low (females) TS stiffness groups. H-reflex latency and amplitude were not significantly different between stiffness groups (p>0.05). Similar Hreflex characteristics across stiffness groups suggested that differences observed in SSR characteristics would have resulted from peripheral influences (i.e. the muscle spindle), as Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. central components did not differ. Because experimental variables known to affect SSR characteristics were standardized across groups, the two groups were assumed to differ only on TS stiffness. However, SSR latency and amplitude did not differ across stiffness groups (p>0.05). Similarly, the relationships between stiffness and SSR latency and amplitude, respectively, were not significant (p>0.05). Previous research indicates SSR sensitivity is related to the muscle length-tension relationship, and likely to series elastic stiffness, but is also dependent on fusimotor drive. It was concluded that the similarity of SSR characteristics in the presence of varying levels of series elastic stiffness was due to the combined effects of series elastic stiffness and fusimotor activity to achieve set-point values for SSR latency and amplitude for standardized kinematic, postural, and neural conditions.