Blog is currently a popular form of knowledge production on the Internet. Research shows that relatively few bloggers produce “filter blogs,” which focus on political knowledge. Most bloggers produce personal journals. This study uses national survey data to determine whether and why people have differential knowledge production in the form of different blogs. As knowledge is a critical indicator of social power, this research also examines whether blogs with different levels of political knowledge demonstrate unequal social power. Results show that bloggers with higher socioeconomic status contribute more filter blogs than lower-status segments. Even among filter bloggers, socioeconomic status, gender, and print-media use are associated with social influence. These findings suggest that a knowledge production gap merits more scholarly attention.