Blogs have been widely used in education since their emergence. Educational researchers and practitioners have integrated blogs into teaching and learning in different subject areas, but does blog use encourage critical thinking? This paper presents a study, which explores peer commenting for critical thinking in blog writing. In order to discover blogging for skill development, survey method and focus group were employed in this study. Results of blog content analysis indicate levels of critical thinking remain constant with or without peer commenting. Based on the findings, recommendations are provided for effective use of blogs for instruction.