Expected visibility (imkan al-rukyah) criterion has been applied to determine the beginning month of Islamic calendar in Malaysia since 1984. This paper aims to investigate chronologically the process behind the decision which was taken to formulate the criterion. It shall provide an analysis of official documents and interviews and followed by a general overview of the development of such criterion in Malaysia. From the point of its astronomical backgrounds the author suggest that this criterion was adopted from the Istanbul Resolution 1978 and formulated based on the reports of moon sighting produced by the Indonesian religious authorities.