SIPTU is an organising union, this means a strong emphasis is placed on recruitment of new members throughout the workforce and activity at all levels of the Union. In order to better undertake its organising role SIPTU underwent a major reorganisation process which was completed in 2010. This saw the Union move to organisation  on an industrial sector rather than regional basis.

A core principle underlying the organising model of trade union activity is giving power directly to Union members. To assist this SIPTU holds regular conferences at various levels of the organisation where committees and members representatives are democratically elected. All Union members are encouraged to play an active role in both implementation and deciding upon SIPTU policy.