Blocking is a theatre term which refers to the precise movement and positioning of actors on a stage in order to facilitate the performance of a play, ballet, or opera.

Blocking is usually carried out by the director of the work during the rehearsal process to give actors surety about where they should move and to ensure sight lines for the audience.

It can be difficult to execute unless the stage design and basic ideas about the positioning of props on stage are known. Each scene in a play is usually 'blocked' as a unit, after which the director will move onto the next scene. The positioning of actors on stage in one scene will usually affect the possibilities for subsequent positioning unless the stage is cleared between scenes. Once all the 'blocking' is completed a play is said to be 'fully blocked' and then the process of 'polishing' or refinement begins. During the 'blocking' rehearsal either the assistant director or the stage manager take notes about where actors are positioned and their movement patterns on stage.