In an effort to improve the structural analysis of transmission towers, this study investigates the effect of bolt slippage on the deflections and member stresses of latticed self-supporting transmission towers. The computer program developed in this study can model tower members as truss and beam elements, can incorporate bolt slippage using an instantaneous slippage model or a continuous slippage model, and can model the connections as semi-rigid (flexible connections) provided moment-rotation data are available. The slippage models require certain parameters, determined from load deformation experiments on typical angle members, in order to accurately incorporate the effect of bolt slippage. Each member of the transmission tower can have its own slippage properties (most importantly the actual amount of clearance slip and the load which initiates clearance slip) depending on its size and connection configuration. The slippage models are applied to several structural analysis problems: a simple one-dimensional bar element, a double-diagonal plane truss, a double-diagonal plane frame with semi-rigid connections, a simple three-dimensional transmission tower, and a full-scale transmission tower. (Abstract shortened by UMI.)