In modern square dancing, the dancers interpret the caller's directions (calls) to determine whom to act with, where to go, and how to get there.
Challenge dancing involves many more calls, and the definitions and choreographic combinations are more abstract and difficult to process.
The same physical movements (e.g. arm turns, passing by) are employed, but deciphering the complex commands and figuring out what you're supposed to do is much more challenging.
Modern western square dancing is organized into a hierarchy of standard syllabus programs (also called "levels").
The higher the program, the more material (i.e. calls) on that list, and the greater ability to recall and handle complexity is required of the dancers.
In each case, the dancers must follow the rules of the basic call, but adjust their actual movements so that they correspond to the positions of the distorted formation.
This requires both a clear understanding of the call definition and the ability to remember where the positions of the formation are without the usual visual and tactile cues.
Frequent use is made in Challenge dancing of fractionalized calls, both explicitly (e.g., the caller asks the dancers to do half of something) and implicitly through concepts.
In addition to local clubs, in many places there are events organized to offer Challenge dancing to the dancers of a larger geographic area on a less-frequent basis (e.g., monthly).
Some general square dance conventions and festivals at the regional or state level include a Challenge hall, but they typically have very limited offerings above C1.
The annual convention of the International Association of Gay Square Dance Clubs (IAGSDC) has a much more extensive Challenge program that is attended by many non-gay dancers.
It has been replaced by MainPAC https://www.mainpac.dance/[1][circular reference] Many other events held annually at various dance facilities attract Challenge dancers from a wide area who are interested in particular levels or callers.