National Council of Teachers of Mathematics
http://www.nctm.org/

The mission of the National Council of Teachers of Mathematics is to provide vision and leadership in improving the teaching and learning of mathematics so that every student is ensured an equitable Standards-based mathematics education and every teacher of mathematics is ensured the opportunity to grow professionally.

Adult Numeracy Network
http://www.std.com/ann

This is an organization, affiliated with NCTM, whose mission statement is "We are a community dedicated to quality mathematics instruction at the adult level. We support each other, encourage collaboration and leadership, and we influence policy and practice in adult math instruction."

Adults Learning Maths - A Research Forum

This is an international association whose object is to promote the learning of mathematics by adults through an international forum which brings together those engaged and interested in research and development in the field of adult mathematics teaching and learning.

Dues are $26.00 per year. Information may be obtained from Katherine Safford, US membership contact, 1317 Curtis Avenue, Point Pleasant, NJ 08742.