See Article IV of the Constitution and Article II of the By-Laws.

At annual conventions, each chapter member, represented by a delegate, is entitled to one vote.

Each chapter is entitled to have one delegate for every ten members or fraction thereof up to 150 members. (i.e.: A chapter with 47 members may have 5 delegates, 4 with 10 votes each and 1 with 7 votes.) If a chapter has between 151 and 250 members, it may have 1 delegate for every 20 members between 151 and 250. i.e.: A chapter with 205 members may have 18 delegates, 15 with 10 votes each, 2 with 20 votes each, and 1 with 15 votes). For a chapter membership of between 251 and 350, the chapter will be entitled to 1 delegate for every 30 members between 251 and 350, etc.