In view of the recent education reform and developments in the research for science learning, alternative and formative forms of assessment are advocated. While teachers in Hong Kong have traditionally adopted mostly paper-and-pencil exercise or tests and summative assessment, science teacher educators need to support teachers in realising this shift in practice. This paper explores junior secondary science teachers' views of implementing alternative assessment tasks in their science classes and hence provide insights to the type and level of support that is required to facilitate this change. The findings provide implications on shifting the current culture of science assessment in Hong Kong from being mainly summative and involving pen-and-paper tasks to implementing alternative assessment tasks. The paper concludes with recommendations of ways to support teachers in achieving changes in their assessment practices.