Advancement to senior chief petty officer is similar to that of chief petty officer. It carries requirements of time in service, superior evaluation scores, and peer review. In the Navy, it is the first promotion that is based entirely on proven leadership performance; test scores do not play a part. A chief petty officer can only advance to senior chief if a board of master chiefs approves, convened every year around March. Senior chief petty officers make up just 2.5% of the total enlisted force of the Navy and overall fall within the top 4% of the enlisted ranks.
In the Coast Guard, advancement to senior chief is similar to other advancements, in that candidates compete with other advancement-eligible chief petty officers. Advancement-eligible chief petty officers are prioritized based on written examination scores, evaluations, award points, time in service, and time in grade. Senior chief petty officers are then selected monthly from this prioritization list as positions become available.
As do chief petty officers, senior chief petty officers take on more advanced leadership duties in their new paygrade. In the Navy, their khaki uniform continues to reflect their responsibility level: It is similar to an officer's uniform, but with different insignia. (In the Coast Guard, petty officers, chief petty officers, warrant officers, and commissioned officers all wear similar uniforms.)
Like petty officers, every chief has both a rate (rank) and rating (job, similar to an MOS in other branches). A chief's full title is a combination of the two. Thus, a senior chief petty officer with the rating of machinist's mate would properly be called a senior chief machinist's mate, the abbreviation of which is MMCS.
Each rating has an official abbreviation, such as MM for machinist's mate, QM for quartermaster, and YN for yeoman. The rating and the rate combined give the abbreviation of a senior chief's full title, such as BMCS for senior chief boatswain's mate. In the expanded form, the title of senior chief always precedes the rating. It is not uncommon practice to refer to a senior chief petty officer by this shorthand in all but the most formal correspondence (such as printing and inscription on awards).
The rating insignia for a senior chief is an eagle with spread wings above three chevrons. The chevrons are topped by a rocker that goes behind the eagle (or "crow", as it is commonly called). An inverted star (similar to the stars on the sleeves of line officers) is above the eagle. This is used on the dress blue uniform. On all other uniforms, the insignia used is the one that has become universally accepted as the symbol of the chief petty officer: a fouled (entwined in the anchor chain) gold anchor superimposed with a silver "USN" in the Navy or a silver shield in the Coast Guard. As in the dress blue insignia, the anchor is capped by an down-pointing star.
In the Navy, officers and chiefs are referred to as "khakis". This is a reference to the color of one of their most common uniforms and is a direct contrast to those in paygrades E-6 and below ("blueshirts").
As of 2005 and after a pilot program taking place on three mine countermeasures ships, the Navy started appointing senior chiefs to command senior chief. Until this time, senior chiefs had a senior enlisted leadership role in the submarine force as chiefs of the boat. This new effort works to formalize leadership at the senior chief level.