This paper is concerned with a survey study of the development and dissemination of the Imamite sect (Twelver Shiah) at Ray. It is said that as a rule the presence of ulema played a great role in the dissemination of their sect in the places they used to dwell. Also mentioned is the historical significance of Ray and its communicational role in the early centuries of Islam, followed by a list of its ulema and hadith transmitters down to the end of the fourth century AH/ ninth century. In mentioning the ulema of the periods concerned, the writer introduces them very briefly, with a mention of the century in which they lived. He then, with evidence, evaluates the hadiths related from them in terms of being thiqa ‘authentic’, mamduh ‘recommended’, and hasan good’; in case they authored any book, their works are also mentioned. Finally, the writer mentions the reasons for the dissemination of Shiah in Iran) the period between the fall of the Ummaids and the office-taking of the Abbasids); he deems the abundance of Iranian companions to the Imams as a crucial factor for this case.