First you have to define functionally illiterate. It means different things to different people. It is a subject of much discussion.

There are some who live a fairly normal life as a functional illiterate. This includes those who never read for pleasure, but read well enough to do all the basic stuff in life. They may be mildly dyslexic or just disinterested.

Many defined as functionally illiterate are from lower income classes and do not do well at all. This category includes the kid who has a low IQ or is dyslexic. They are held back in school and often wind up as drop outs. They read so poorly they can't fill out some forms or read some instructions. They are barely above illiterate.

My youngest daughter was in gifted classes until she was half way through high school. Her inability to enjoy reading (she hated it) caught up with her and she struggled a little for the last two years.

She was a C student in college and dropped out after 3 years. She has begun to read for pleasure in the last 4-5 years but her taste in literature is also C average at best. :) She is close to being a functional illiterate by some definitions.

Too bad Mary Anne is not around to chime in on this subject. She is brilliant on the subject and could answer all your questions better than me.