The Preparation of the Gifts (cf. nos. 139-146) is carried out by the principal celebrant, while the other concelebrants remain at their places.
After the prayer over the offerings has been said by the principal celebrant, the concelebrants approach the altar and stand around it, but in such a way that they do not obstruct the execution of the rites and that the sacred action may be seen clearly by the faithful. They should not be in the deacon’s way whenever he needs to go to the altar to perform his ministry. The deacon exercises his ministry at the altar whenever he needs to assist with the chalice and the Missal. However, insofar as possible, he stands back slightly, behind the concelebrating priests standing around the principal celebrant.