Urban design and architecture are among multi-disciplinary subject-areas dealing with a wide range of topics starting from humanities and ending with natural sciences. This unique character makes the selection and application of research methods very difficult. To add to the existing knowledge on this subject area, the authors tried to introduce common research methods in architecture and urban design. The first step to achieve the goal is identification of main research paradigms. In this part, the classification done by John W. Creswell has been accepted as the basis, and four main paradigms have been identified as the theoretical basis of research methods including: positivism, interpretivism, pragmatism and critical theory. The recognition of research strategies or typologies is the next step. After developing a draft classification, it was necessary to justify the results through an empirical study. To do so, through a selective sampling method, a number of research papers which have been published in Iranian scientific journals have been chosen. After thorough comparison of the results, the final diagram has been drawn. The diagram illustrates main research paradigms, together with different research strategies. It has the potential to be completed through time, and presents the general classification of common research methods in the field of urban design and architecture. To give a more comprehensive knowledge on each research method, a table has been developed which could be filled later on. It consists of following information: paradigm, approach, goal and implementation (data gathering methods and data analysis methods). The results indicate the dominance and importance of qualitative and mixed research methods in architecture and urban design studies.