A reliable characterisation of the response of mechanical dowel-type timber connections is essential for the development of design methods. The European standard EN 26891 and the American standard ASTM D1761 provide guidelines for the experimental tests of connections made with mechanical fasteners and have been widely adopted in research practice. However, differences in loading protocols, test set-ups, boundary conditions, and displacement measurements hinder a direct comparison between experiments, making the reliability and transferability of results difficult to assess. To address this gap, the RILEM TC TPT is developing a round-robin programme to assess the reproducibility and repeatability of tests on timber connections in accordance with EN 26891 and ASTM D1761 across various laboratories. The specific objectives of this initiative are as follows: (i) identify sources of variability in testing outcomes related to equipment, operator, and procedural interpretation; (ii) quantify the influence of specimen preparation and material sourcing on the evaluation of the mechanical performance of dowelled timber joints; and (iii) provide a basis for improving standardisation in test methods and reporting across laboratories. The programme is structured in two phases: (i) centralised material supply with Laminated Veneer Lumber to minimise material variability, focusing on the influence of specimens’ assembly and test set-up, and (ii) independent and local sourcing of Glued Laminated Timber to capture local material and fabrication influences. With this, the round-robin experimental campaign aims to contribute to more reliable testing procedures and to the refinement of international design standards for timber connections.