Purpose: Nearly 50 years ago, Durkin (1978-1979) conducted a seminal observation study on reading comprehension teaching in Grades 3 through 6. She reported that teachers rarely taught reading comprehension (less than 1% of instructional time). Since then, we have gained substantial knowledge about teaching reading comprehension. We aimed to comprehensively review direct observation studies of reading instruction to understand the extent to which recommended comprehension practices are implemented in schools. Method: A systematic search of the extant literature identified 66 observation studies of reading comprehension instruction for children in K-12 schools, including a total of 1,784 teachers. We employed a mixed-method systematic review to address the research questions. Results: Integrated analyses revealed that reading comprehension instruction infrequently aligned with research-based practices. Findings revealed that, on average, 23% of instructional time during reading/language arts instruction was dedicated to reading comprehension. Like Durkin's study (1978-1979), the results indicated that teachers spent much of this time engaging in initiation-response-evaluation conversation patterns rather engaging students in extensive discussion of text or teaching knowledge or practices (e.g. text structure, reading comprehension strategies) that support reading comprehension. However, analyses suggested that studies conducted after 2000 reported more research-based reading comprehension practices than earlier studies. Conclusions: These findings suggest a substantial gap persists between the reading comprehension practices identified as research-based and those observed in typical practice. There is a need for renewed efforts to prioritize reading comprehension instruction in policy and practice.