It is widely recognized that the 12 percent of all youth in American public schools who have disabilities comprise a set of students with distinct capacities and needs. Federal legislation, including the most recent updates to the Individuals with Disabilities Education Act (IDEA) in 2004, identifies different disability groups and mandates that students in each group have access to a free and appropriate public education. How youths' characteristics, experiences, and challenges vary by disability group remains of interest, particularly given the changing educational, social, and economic landscape that might affect youth with different disabilities in different ways. The National Longitudinal Transition Study (NLTS) 2012 provides updated information on youth with disabilities in light of these changes, to inform efforts to address their needs. Sponsored by the U.S. Department of Education under a congressional mandate to study IDEA 2004 and the students it serves, the NLTS 2012 describes the backgrounds of secondary school youth and their functional abilities, activities in school and with friends, academic supports received from schools and parents, and preparation for life after high school. Through surveys in 2012 and 2013, the study collected data on a nationally representative set of nearly 13,000 students-mostly those with an individualized education program (IEP) and expected to receive special education services. The study also includes students without an IEP, who either have no identified disability or who have an impairment that does not qualify them for special education but allows them to receive accommodations through a 504 plan under the Rehabilitation Act, another federal law pertaining to the rights and needs of youth with disabilities. This second volume of findings from the NLTS 2012 focuses on youth with an IEP only and the similarities or dissimilarities across 12 disability groups defined by IDEA 2004. The assessment of diversity among the disability groups in the decade following IDEA 2004 suggests several key points: (1) Youth with intellectual disability and emotional disturbance are the most socioeconomically disadvantaged groups and the most likely to attend lower-performing schools; (2) Difficulties with health, communication, and functioning independently are most prevalent among youth with autism, intellectual disability, multiple disabilities, and orthopedic impairments; (3) The groups that most commonly face health and functional challenges are also less engaged with friends and in school activities, but youth with emotional disturbance are most likely to get into trouble; (4) Youth with autism, intellectual disability, and multiple disabilities are most likely to receive academic modifications but least likely to receive some other forms of academic support; and (5) The same three groups--youth with autism, intellectual disability, and multiple disabilities--are least likely to take steps to prepare for college and employment. These findings highlight some differences in the challenges that youth with an IEP faced in the decade after IDEA 2004, depending on their disability. Although the characteristics and experiences described capture only a subset of those discussed in this volume, prior research suggests that they could be important indicators of students' later outcomes. The following are appended: (1) Technical notes and methodology for volume 2: Comparisons across disability groups; (2) Detailed tables for chapter 2 of volume 2: Comparisons across disability groups; (3) Detailed tables for chapter 3 of volume 2: Comparisons across disability groups; (4) Detailed tables for chapter 4 of volume 2: Comparisons across disability groups; (5) Detailed tables for chapter 5 of volume 2: Comparisons across disability groups; and (6) Detailed tables for chapter 6 of volume 2: Comparisons across disability groups. [For the Executive Summary, see ED573353; For Volume 1, see ED573341.]