It might be argued that Castlebar R.F.C. has pioneered its own age of reformation since it was recognised at an Irish Rugby Football Union(IRFU) meeting in Corless' Burlington Diningrooms in December 1885. It is recorded that Castlebar was one of seven clubs to be represented at this meeting in Dublin where the Connacht Branch was formed. In fact it was the only Mayo club with Ballinasloe, Galway Town, Galway Grammar School, Queen's College, Galway and Ranelagh School, Athlone the other clubs in attendance.
The progress of the club during this period remains vague. There is evidence of some playing activity in 1903 before a spell of inactivity, possibly precipitated by the First World War, brought the curtain down on the club.
The club was founded, or perhaps reformed, in 1928 but only affiliated to the Connacht Branch in November 1934. There is further evidence, however, that the Castlebar R.F.C. was reformed in 1939, suggesting that rugby action on the fields of play during the 1930s was somewhat - if not severely - limited.
However, the reformation of 1939 brought with it a change from the black and amber strip which had marked the club's embryonic era, to the current colour combination of sky blue and navy. This change was the result of the involvement of a local businessman who donated a set of jerseys in the colours of his former school, Castleknock. During the 1940s and 1950s Castlebar was one of four Mayo clubs to compete in the Connacht Junior League. The club was also honoured during this era when Bernie Egan from Blackfort, Castlebar, played for both his country and his province at representative level.
The club again folded in the mid-60s and remained dormant until 1971 when the age of reformation was revisited yet again. Victory visited Castlebar that same year when they secured the Connacht Junior B League.
Retaining the sky blue and navy strip, the club wandered from pillar to post until 1973 when they made Airport Field, Breaffy Road, their quasi-permanent home. After ten years there, Castlebar R.F.C. relocated to Cloondeash, the club's present dwelling, where a clubhouse and dressing room facilities were soon developed. These were renovated during the mid-90s when new dressing rooms were added to the venue.
The club briefly participated in the All-Ireland League following its inception during the mid-90s when it amalgamated with Westport to represent Mayo.
Castlebar repeated their Connacht Junior B League success in 1988, the season after the club was narrowly defeated in its first Connacht U-18 Cup Final. By 1996 Castlebar R.F.C. was again represented in a Connacht Cup Final. On this occasion the club participated in the province's blue riband event, the Connacht Junior Cup Final, only to go down to Monivea at the Galway Showgrounds.
The club has since established itself as one of Connacht's most consistent Junior League Division 1 teams and is widely respected at this level throughout Connacht. At present, Castlebar R.F.C. is endeavouring to re-establish a thriving underage structure and the new floodlights at Cloondeash plus a second playing field offer an ideal platform to develop. Reformation, finally, seems a thing of the past.