Reiki is taught in levels and through attunements performed by a Reiki master. Generally, there are three levels, but the Usui/Tibetan schools added the level IIIa.

Reiki Level I (Sho Den in Japan) is taught to those who want to use the Reiki energy. The information are given by a Reiki instructor, trained to teach Reiki and to pass attunements. Traditional Usui systems use four attunements for the level I. A Reiki Level I class includes, in general, the Reiki history, the Reiki principles and the hands positions, when you send Reiki to you or to the others. Then the attunement is performed. Some schools use only one attunement for the level I. 

Some of the schools give information about the effects of the energy to the organs and indications about the affections and how to treat them. Some schools give information about charkas (energy vortexes).

At Reiki Level II (Oku Den in Japan) the three Reiki Symbols are taught and an attunement is performed to the student. Reiki Level II is a greater commitment to Reiki. Some say this level heals on the emotional level, like level I on the physical level. Many others think that Reiki works always on all levels. The student learns the Power Symbol, the Mental/Emotional Symbol and the Distant Symbol. There are taught their meanings and their applications. Some schools require a lenght of time before the level II can be taken.

Level II includes, in general, the three symbols, the Mental/Emotional healing, the Distant healing and another attunement.

The non-traditional schools add scanning and beaming.

Reiki Level III (Master Level) (Shinpi Den in Japan) is the Reiki  Master Level. It is taught the Usui Master Symbol (the empowerment symbol). This symbol completes the three symbols taught at Level II. The students are trained to perform a Reiki attunement. This level includes the Usui Master Symbol, its meanings and applications, the attunement process and instructions on how to teach others.

Non-traditional schools add three symbols : the tibetan Master Symbol, the Fire Serpent Symbol and the Raku Symbol. They also use, in the attunement process, some Tibetan breathing techniques and the microcosmic orbit. The Usui/Tibetan schools added the Level IIIa between the Level II and the Master Level. This new level is called Advanced Reiki Training.