In this study, we assessed how well children's counting books are aligned with current research on children's emerging numeracy. We coded structural and content features of 120 readily available counting books, focusing on features of how numbers were presented, features of items and sets to be counted, and structural features that varied across books. We found that several features that may support learning to count—such as presenting numbers in ascending sequence—were frequently identified in the books we coded; but we also found that features that may interfere with learning to count also occurred frequently, such as presenting multiple distractors on pages with items to be counted. Explicit or even implicit emphasis on counting principles such as cardinality were quite infrequent across most books, and nearly half of all books had at least some pages depicting inconsistencies between the number of items in an illustrated set and the numeral or number word accompanying the set. There was some co-occurrence of select features: Books with many distractors were more likely to have obstructed items within sets to be counted, and were less likely to explicitly draw links between sets and numerals or number words, compared to books that were relatively distractor-free. Considered together, these findings highlight the need for research on how features of counting books and other early mathematics-related books may affect shared-reading and the development of children's numerical and mathematical thinking.