Pearse’s interest in Irish culture dated from his teenage years. In 1898 he became a member of the Executive Committee of Conradh na Gaeilge. He graduated from the Royal University in 1901 with a Degree in Arts and Law. Pearse’s literary output was constant, and he published extensively in both Irish and English, becoming the editor of An Claidheamh Soluis, the newspaper of the Gaelic League. He was a keen believer in the value of education, and established two schools, Coláiste Éanna and Coláiste Íde, devoted to the education of Irish children through the Irish language. One of the founder members of the Irish Volunteers, and one of the authors of the Proclamation, Pearse was present in the GPO during the Rising, and was Commander in Chief of the Irish forces.
Thosaigh Mac Piarais ag cur suime i gcultúr na hÉireann agus é ina dhéagóir. In 1898 rinneadh comhalta den Phiarsach ar Choiste Feidhmiúcháin Chonradh na Gaeilge. Bhain sé céim amach san Ollscoil Ríoga in 1901, céim sna Dáin agus sa Dlí. Bhíodh an Piarsach ag scríobh go seasta agus d’fhoilsigh sé cuid mhór saothar i nGaeilge agus i mBéarla. Ceapadh ina eagarthóir é ar pháipéar nuachta Chonradh na Gaeilge, An Claidheamh Soluis. Chreid sé go láidir san oideachas agus bhunaigh sé dhá scoil, Coláiste Éanna agus Coláiste Íde, a bhí dírithe ar oideachas trí Ghaeilge do pháistí na hÉireann. Bhí an Piarsach ar dhuine de bhunaitheoirí na nÓglach agus bhí sé páirteach i gcumadh Forógra na Poblachta. Bhí sé in Ard–Oifig an Phoist le linn an Éirí Amach, áit a raibh sé ina Phríomh-Cheannfort ar fhórsaí na hÉireann.