This study compared the kinematic and electromyographic (EMG) gait patterns of able-bodied adults at natural speed in contrast to extremely slow overground and treadmill walking speeds. Kinematic and EMG data were collected at three speeds (self-selected, 0.30 m/s, and 0.20 m/s). Eighteen subjects were evaluated for trunk and lower-limb motion and EMG of five lower-limb muscles. Significant reductions were found in segmental motion between natural speed and both slower gait speeds, accompanied by an expected reduction in cadence and stride. EMG patterns at slower speeds showed changes in timing and reduced magnitudes. Phasic timing of the proximal muscles showed the most changes with predominant coactivation, whereas the distal muscles remained consistent with the pattern at natural self-selected speed. Overground versus treadmill gait patterns revealed minimal differences. Consideration of the effects of slower walking speed may help clinicians create interventions to target primary gait deficits on overground or treadmill walking.