This paper investigates the wall effects on the settling velocity of a falling ball in concentrated suspensions. The model suspensions consist of uniform neutrally buoyant spheres in a viscous Newtonian suspending fluid under conditions such that only hydrodynamic forces exert an appreciable effect. A number of previous studies have focused on determining the average velocity of the settling particle along the centerline or axis of the containing cylinders. The objective of this study is to determine the wall effects experienced by the falling balls as they settle off-center or eccentrically at a radial distance b from the centerline in a cylinder of radius R. We find that in the dilute suspensions (volume concentration of solids, phi = 10%), off-center wall effects are indistinguishable from those in pure Newtonian fluids. For the moderately concentrated suspensions (phi = 30%), off-center wall effects begin to deviate from Newtonian behavior as the ball approaches the wall (b/R > 0.5) and the ball settles slower than it would in a Newtonian fluid with the same apparent viscosity. In a highly concentrated suspension (phi = 50%), the Newtonian region in the center of the cylinder is much smaller (b/R < 0.3) and wall effects are significantly stronger than those found in the moderately concentrated suspension. These results indicate that current suspension constitutive models that assume generalized Newtonian behavior for concentrated suspensions must be reexamined as wall effects are much larger and extend further into the suspension than previously thought. (C) 2003 Elsevier B.V. All rights reserved.