The one-dimensional, single-occupancy lattice gas exhibits highly cooperative particle motion and provides an interesting challenge for theoretical methods designed to describe caging in liquids. We employ this model in an effort to gain insight into caging phenomena in more realistic models of liquids, using a diagrammatic kinetic theory of density fluctuations to develop a series of approximations to the kinetic equations for the van Hove selfcorrelation function. The approximations are formulated in terms of the irreducible memory function, and we assess their efficacy by comparing their solutions with computer simulation results and the well-known subdiffusive behavior of a tagged particle at long times. The first approximation, a mode coupling theory, factorizes the 4-point propagators that contribute to the irreducible memory function into products of independent single-particle propagators. This approximation fails to capture the subdiffusive behavior of a tagged particle at long times. Analysis of the mode coupling approximation in terms of the diagrammatic kinetic theory leads to the development of two additional approximations that can be viewed as diagrammatic extensions or modifications of mode coupling theory. The first, denoted MC1, captures the long-time subdiffusive behavior of a tagged particle. The second, denoted MC2, captures the subdiffusive behavior of a tagged particle and also yields the correct amplitude of its mean square displacement at long times. Numerical and asymptotic solutions of the approximate kinetic equations share many qualitative and quantitative features with simulation results at all timescales.liquids | mode coupling D ense liquids exhibit highly correlated motions of constituent particles. Understanding the dynamics of particle motion can give deep insight into both microscopic and macroscopic properties of liquids, including the diffusive properties of labeled particles and macroscopic transport coefficients (1). In many dense liquids, correlated particle motion is closely related to the phenomenon of caging, in which the motion of each particle is severely constrained by the presence of other nearby particles. Each particle is said to be surrounded by a "cage" of neighboring particles, and in order for a particle to move an appreciable distance, a collective rearrangement of its caging particles must occur.Characterizing the breakdown of a cage is of paramount importance in understanding the properties of many liquids, including atomic, polymeric, and colloidal fluids. For example, caging is thought to dominate the dynamics of liquids near the glass transition, and it plays an important role in polymer physics, where entanglement effects at the microscopic level affect macroscopic properties such as viscosity and elasticity.This article examines the development of approximate kinetic theories for a one-dimensional, single-occupancy lattice gas in which particles undergo symmetric, continuous-time random walks subject to the constraint that they cannot pass through eac...