The principal elements of the Crest are as follows:

• The River Liffey represents a source of life and growth through the ages.
  
• The Obelisk, which was commissioned by the Conollys of Castletown in 1739 to provide employment during famine times, reminds us of our ancestors and our heritage.
  
• The Window is from the ancient church of St. Mochua in Tea Lane and it together with the torch are symbols of light, wisdom and knowledge.
  
• The steps are from the wall of St. Mochua's church and each of the eight steps represent the years of learning and development in Scoil Mochua.