use of headings in APA style

APA's heading style consists of five possible levels of subordination. Level first is highest level and level fifth is lowest level. Most papers will use two or three levels. Levels are always use consecutively, beginning with level one.
1.Level 1: Centered, Boldface, Uppercase and Lowercase Headings
2.Level 2: Left-aligned, Boldface, Uppercase and Lowercase Heading
3.Level 3: Indented, boldface, lowercase heading with period.
4.Level 4: Indented, boldface, italicized, lowercase heading with period.
5.Level 5: Indented, italicized, lowercase heading with period.



http://en.wikipedia.org/wiki/APA_style