In order to accommodate patients to new foot orthoses over time, two steps are required: The first is to obtain a baseline reading of the immediate effects across several weeks to ensure consistency. The second step is to look at changes with progressively longer wear periods similar to what occurs in general practice. This study addressed the first step. The purpose of this study was to determine whether the baseline reading of the immediate effects of foot orthoses on comfort and lower extremity kinematics, kinetics, and muscle activity is consistent between days. Participants were 21 recreational runners who volunteered for the study. Three orthotic conditions (posting, custom-molding, posting and custom-molding) were compared to a control (flat) insert. Lower extremity kinematic, kinetic, and EMG data were collected for 108 trials per participant and condition in 9 sessions for each person for running at 4 m/s. Comfort for all orthotic conditions was assessed in each session using a visual analog scale. Statistically significant session effects were detected using repeated-measures ANOVA (a = .05). Three of the 93 variables had a significant session effect. A significant interaction between orthotic condition and session was observed for 6 of the 93 variables. The results of this study showed that the effects of foot orthoses on comfort, lower extremity kinematics, kinetics, and muscle activity are consistent across a 3-week period when the wear time for each condition is restricted. Thus, foot orthoses lead to immediate changes in comfort, kinematics, kinetics, and muscle activity with limited use. These immediate effects of foot orthoses on comfort, kinematics, kinetics, and muscle activity are consistent between days.