DS's teacher told me that he's definitely reading at least 2nd grade level and she was surprised to hear that he doesn't like to read. Maybe we just need to find the books that he's really interested in. We were just reading a book about ancient Egypt last night. At the end of the chapter, there is a chart showing the symbols that represented the English alphabets. After reading the chapter, he immediately started writing my DH's name and his name in the symbols. He also made his own chart showing all the alphabets matching the symbols. We probably should find books like this with graphics and things he likes (such as symbols, maps, flags) so he reads the text and have something fun for him to look at as well...
When my son was K-2nd grade he mostly read non-fiction books. I couldn't really get him to read chapter books. We had (still have) tons of big thick books about dinosaurs, dragons, animals, Ancient Egypt, you name it. The lexile level of these books are are way past "2nd grade' reading.
Keep in mind that most 'early' chapter books aren't great literature. In order to fit the genre they use limited vocabulary intentionally and short chapters. Early chapter books are fairly "new" genre. (Didn't really exist when I was a kid, and early chapter books were things like Frog & Toad.) Kids used to go from reading longer picture books straight to those now labeled for the 8-12 year old range. And while many kids find them a good stepping stone it's really not a requirement to learning how to read. Another good stepping stone for reluctant readers available these days are kids graphic novels.