SOMETIMES principalships are like buses - coming in threes. At the moment there are three opportunities in the Dublin area.

It's possible that the first lay principal will soon be appointed to a long established girls' secondary school in Dublin. The post of principal has been advertised by Muckross Park College, Donnybrook, a girls' secondary school founded by the Dominican Sisters 97 years ago. Sister Norah O'Connor, principal for 16 years, will retire later this year. There are 670 students and 38 full-time teachers at Muckross.

St Dominic's Secondary School in Ballyfermot, Dublin, is also looking for a new principal from next August. The all-girls school, of which the Dominican Sisters are trustees, has 560 pupils. Application forms are available by sending a large SAE to the Secretary, Board of Management, at the above address.

Another opportunity is offered by St Mary's College in Rathmines, Dublin. Closing date for applications to this boys' school run by the Holy Ghost Fathers is next Tuesday. St Mary's has 700 pupils in preparatory and secondary schools. Application forms for the post are available from the President, St Mary's College, Rathmines, Dublin 6. Current principal Frank Conlon, the school's first lay principal, is retiring after nine years. The school has a staff of 31, including part-time and full-time.