Color of the Priests Robes

During Lent the priests wear Purple for Mass except on Laetare Sunday (they wear rose), Palm Sunday and Good Friday (they wear red).
  
 Laetare Sunday
 (Rose Sunday)
 is the 4th Sunday of Lent. 
 
 It takes its name from the opening words of the Mass, the Introit's "Laetare, Jerusalem". ("Rejoice, O Jerusalem") 
 
 On this Sunday, the Church lightens the liturgical atmosphere, replacing somber violet vestments with bright rose, putting flowers on the altar, and allowing use of the organ.

These are external symbols of the joy that we are meant to feel as we prepare for the Easter feast – whether we are new Catholics preparing to receive the sacraments of initiation at Easter or life-long Catholics called to a life of ongoing conversion.
  
 Israel 66:10-11  Rejoice with Jerusalem and be glad because of her, all you who love her; Rejoice with her in her joy, all you who mourn over her— So that you may nurse and be satisfied from her consoling breast; That you may drink with delight at her abundant breasts!
 
 Psalm 122:1  I rejoiced at the things that were said to me: we shall go into the house of the Lord. Glory be to the Father.
 
 
The Priest wears red on
 Palm Sunday and Good Friday symbolizing the passion of Christ and the blood He shed upon the cross.