Membership in the Trefoil Guild is open to women over 30 who pay the annual membership fee, and who have been or are willing to be enrolled. Members may be active in other aspects of Guiding. Trefoil Guild members meet for friendship, service and to keep the spirit of Guiding alive. All members are entitled to wear the Trefoil Guild pin either in or out of uniform.
In PEI, two Trefoil Guilds currently exist, one in Charlottetown, and one in Summerside. Trefoil Guild members meet monthly. Members of the Trefoil Guild are involved in various ways across PEI. Some may volunteer occasionally to help a unit out with a special activity or to share a skill, some sit on Provincial Committees, they oversee archives, and help out on occasion with Provincial Rallies and events.