Like trade union numbers generally, membership of Siptu has grown over the last three years as the workforce has expanded.
Siptu's membership levels are about 200,000- 260,000, depending on the way the figures are calculated. It has about 260,000 members on its books - a figure with which a recent national survey carried out by Behaviour & Attitudes broadly agreed.
However, its "financial membership", the level of income from members divided by a formula which assumes that everyone pays a net contribution, weekly stands at just under 200,000. Siptu leaders believe that this figure can understate actual membership as the number of people contributing is in flux constantly due to the mobility in the workforce.
Jack O'Connor said that there had been a net growth in membership over the last few years despite the decline in its traditional base of manufacturing. However, he said that the union had restructured its operations and had proved very successful in organising in private sector services, construction and in health.