Pull-out and push-out measurements were performed on glass fibres in an epoxy resin to determine the dependence of bond strength on test temperature and on fibre surface treatment. A comparative analysis of the two techniques was carried out to elucidate elementary processes of polymer-fibre debonding and to determine energy values for adhesional bonds. Differences in bond strength values for pull-out and push-out tests were attributed to failure mechanisms that were either interface-controlled or matrix-controlled. Evidence for the different failure mechanisms characteristic of the two test techniques was provided by an estimation of failure parameters, such as the activation energy for debonding. Failure mechanisms also were manifest in AFM images, showing differences in topography and roughness that depended on fibre surface treatment, test geometry, and test temperature.