A blitzkrieg start by St Michael's paved the way for a comfortable victory at Donnybrook.
Barry Fitzpatrick kicked over an early penalty and then full-back Michael Heaney showed quick hands to send Chris Carey over on the quarter-hour.
Fitzpatrick then converted his own try. Michael's captain Ronan Kelleher broke and set up Carey in the corner to put his side in a commanding 20-0 half-time lead.
Clongowes began to come into it after that, with Sean McCrohan impressive.
And although Fitzpatrick added his second penalty shortly after the break, Clongowes finished strongly.
Jack Moore finally went over midway through the half, and then a skipped pass released Sean McCrohan for a second try on the hour mark which Stephen Gildea converted.
Clongowes Wood College – R Lemess; J Garty, P Delap, T Wisniowski, B Maher; M Silvester, N McDermott (A O'Sullivan 35); J Martin, C Slattery (T Dooley 42), E Carroll; S Gildea, D Walsh (J Savage 33); J Moore, P Nulty, S McCrohan.
St Michael's College – M Heaney (R Frankling 35); H McIntyrne, J Kelly, J Hickey, C Carey; H Byrne, P O Beirne; R Kelleher (R Melvin 55); T Glynn (M Kennedy 50), S Griffin; J Kennedy, M O'Donahoe; R Duffy, O Dowling, B Fitzpatrick.
Ref – B White (ARLB)