The 2003 National Assessment of Adult Literacy (NAAL) assessed the English literacy of incarcerated adults for the first time since 1992. The assessment was administered to approximately 1,200 inmates (ages 16 and older) in state and federal prisons, as well as to approximately 18,000 adults (ages 16 and older) living in households. Three types of literacy were measured: (1) prose literacy: The knowledge and skills needed to search, comprehend, and use information from continuous texts; (2) document literacy: The knowledge and skills needed to search, comprehend, and use information from noncontinuous texts; and (3) quantitative literacy: The knowledge and skills needed to identify and perform computations using numbers that are embedded in printed materials. This report presents the findings from the 2003 prison adult literacy assessment. The report includes analyses that compare the literacy of the U.S. prison population in 2003 with the literacy of the U.S. prison population in 1992. It also includes analyses that compare the literacy of the prison and household populations in 2003. (Contains 85 tables, 72 figures, and 8 footnotes.)