The following is reprinted from the National ALD website:
You've been invited to join one of the most prestigious honor societies in the nation! Alpha Lambda Delta has over 80 years of tradition honoring the best first year students at over 250 institutions of higher education.
Alpha Lambda Delta is an honor society for students in their first year at an institution of higher education. We're a national organization that's been in existence since 1924. We recognize those students who have succeeded in maintaining a 3.5 or higher GPA, or are in the top 20% of their class, in their first year. Alpha Lambda Delta's mission is to "encourage superior academic achievement... to promote intelligent living and a continued high standard of learning, and to assist students in recognizing and developing meaningful goals for their unique roles in society."
You were invited because you've attained a 3.5 or higher GPA in your first year or term in higher education, and you're in the top 20% of your class after the first year or term. You've already earned the recognition that Alpha Lambda Delta offers - now, all you have to do is accept it.
Lifetime National dues for Alpha Lambda Delta are $20. Many local chapters also charge dues for membership, but for most students, joining Alpha Lambda Delta for life costs less than $50. Once you pay your dues once, you'll never be charged again.