usmleUSMLE has announced that a unified content outline will now be used for all the USMLE Steps including Step 1, 2 CK & CS. 

The unified content outline consists of 18 sections. Fourteen of these sections primarily correspond to organ systems; the remaining four sections are General Principles; Multi-system Processes and Disorders; Biostatistics, Epidemiology/Population Health, and Interpretation of the Medical Literature; and Social Sciences.

Most organ systems are partitioned into Normal Processes and Abnormal Processes, and include subcategories of specific disease processes.

While the unified outline is common to all exams, each Step will continue to have test specifications specific to that particular Step. Each Step exam will emphasize certain parts of the outline, and no single examination will include questions on all topics in the outline.

Examinations released in 2014 will be built using the new unified content outline. Test specifications using the unified outline will be published by USMLE in early 2014. For Step 1, Step 2 CK, and Step 2 CS, the changes will be subtle, and the examinations will be similar in content to previous years. Step 3 examinations administered on or after November 1, 2014 will include more substantial changes in content; additional information about changes to Step 3 is available.