Full scale lateral load tests were performed on four piles located at various distances behind MSE walls. Three of the four test piles were production piles used to support bridges, and the other pile a production pile used as part of the bridge abutment. The objective of the testing was to determine the effect of spacing from the wall on the lateral resistance of the piles and on the force resisted by the MSE reinforcement. Lateral load-displacement curves were developed for pile at various spacing and with various reinforcement ratio (reinforcement length, L divided by wall height, H). The force in the reinforcement was measured using strain gauges. Lateral load analyses were performed to determine the minimum spacing required to eliminate any effect of the wall on the pile resistance (p-multiplier of 1) and the reduction in soil resistance at closer spacings (p-multiplier less than 1). With the addition of the data fro Price (2012) tentative curves have been developed showing p-multiplier vs. normalized spacing behind wall for a length to height ratio of 1.6, 1.2, and 1.1. The data suggest that with a L/H ratio of 1.6, a p-multiplier of 1 can be used when the normalized distance from the back face of the MSE wall to the center of the pile is at least 3.8 pile diameters. When the L/H ratio decreases to 1.2 and 1.1 a p-multiplier of 1 can be used when the pile is at least 4.5 and 5.2 pile diameters behind the wall respectively. For smaller spacings, the p-multipliers decreased essentially linearly with normalized distance from the wall. A plot showing the increased load in the reinforcement as a function of distance from the pile has been developed. The data in the plot is normalized to the maximum lateral load and to the spacing from the wall to the pile. The best fit curve is capped at a normalized tensile force of approximately 0.12. The data show that the increase in tensile force on the reinforcement when a lateral load is applied to the piles decreases exponentially as the normalized distance from the pile increases. The plot is limited to the conditions tested, i.e. for the reinforcement in the upper 3 ft. of the wall with L/H values at 1.2.