Experience has shown that ... personalities ... may be grouped into various major categories, and for purposes of studying them this is a helpful device. Classifications must never be taken too seriously—they ruin much thinking—but the fear to use them has prevented much more thinking.
—Karl A. Menninger, The Human Mind
This is another personality sorter, one more involved than the Kiersey sorter. This one has 9 categories, but you can be in two categories at once, and each category has 9 levels of development. I found it difficult to place myself in the categories. There is an on-line test available at the Enneagram Institute but it costs $10.