Internationally projects exhibit time and cost overrun. It is observed that problems during design development contribute significantly to delays. In India, projects undertaken by government were largely planned and designed by departmental planners and engineers. However, after globalization, projects have increased in number resulting in design outsourcing, but with attendant challenges. The paper is aimed at identifying and analysing factors in the design development phase that can have impact on project success. 30 factors related to design development were identified through two separate brainstorming sessions. A questionnaire was then administered to determine importance ranking of these factors. Relative importance index (RII) was used to prioritise these factors. Top ten factors in design development identified using RII include structural design parameters, soil investigations, design quality control, topographic survey, and architectural design parameters. The results can help firms improve their design development practices by prioritising activities that could have more impact on project performance.