Today in Chinese Mainland, by 成份 (also or better 成分) we mean a person's profession (including student).

It is worth noting that before and during those turbulent years of the Cultural Revolution, a person's 成分 also had strongly political implications, because a person's 成分 was then largely defined by his/her family background that was mostly traced back to before 1949, and this in turn was viewed as an important indicator for a person's social status.

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Note added at 31 mins (2007-09-20 12:02:51 GMT)
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It definitely has nothing to do with one's marriage status!

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Note added at 49 mins (2007-09-20 12:21:01 GMT)
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As can be seen from the link provided by Shirley, in China today 成分 has become so outmoded a concept that many people are perplexed as how they should fill in the blank when they come across this item. My equating it with "profession" is a big progress from its former high political nuance of "social origin, class status". After all, we must 与时俱进 (go with the time).

However, as this item appears in a birth registry, I believe 成份 here must still be understood as this baby's "family background", that is, what his parents do as profession: farmer, worker, business owner, teacher, etc.

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Note added at 1 hr (2007-09-20 12:32:42 GMT)
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Sorry, 与时俱进 is better translated as "go with the times" instead of "go with the time".

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Note added at 1 hr (2007-09-20 12:35:47 GMT)
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If this birth registry keeps the person's data updated, it is also possible 本人成份 here refers to his/her "Profession".

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Note added at 5 days (2007-09-26 08:54:23 GMT) Post-grading
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http://www.szour.cn/magazine/2005n4q/11.htm

如何填写履历表

个人成份

个人成份是指个人早先的主要经历或职业，如工人成份、学生成份等等。然而这个“早先”早在什么时候，先在什么时候，这是人们普遍难以掌握的。在人事组织工作中实际上常把一个人参加革命工作（过去把正式参加国家工作称为参加革命工作）之前的主要经历或职业称之为个人成份。一个大学毕业生由国家分配走上工作岗位，那么他的成份就是学生。又如一个人他原来是工人，后来参军或提升为干部，他的个人成份就是工人。

设计“个人成份”这个栏目是改革开放前的产物，现在的履历表大多设计“个人身份”这样的栏目。



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Note added at 5 days (2007-09-26 08:59:05 GMT) Post-grading
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家庭出身

家庭出身是指个人在取得独立经济地位之前供给自己经济来源的父母或其他抚养人的社会职业或社会地位。在中华人民共和国成立前后，一般家庭出身有如：工人、贫民、职员、资本家、贫农、中农、地主、革命军人、干部、高干等等。改革开放后，一般家庭出身有如：工人、职员、自由职业者、公务员、干部、农民等。这前后两个时期最大的区别是：在农村不再有贫农、富农、地主之分了，一般统称农民；在城市过去泛称干部的现在有的要称职员，有的要称自由职业者，如过去企业的管理者统称干部，现在其中大部分应是职员了。这类问题稍微复杂一些，在此不宜展开去写。

http://china.zjol.com.cn/05china/system/2007/02/08/008165013...

人事档案上保留个人成分妨碍了谁

幸亏广东的几位人大代表提名，要不然我还真险些忘了自己的家庭出身和个人成分，当然，还有我祖上三代的成分。这份代表建议说，应取消现行人事登记表一些过时的内容，诸如“家庭成分”、“个人成分”等栏目。原因在于，大中专毕业生可认定为“干部”，普通高中、技校毕业生则认定为“工人”，这明显妨碍了这部分人(其中不乏具有某些专长的人才)的积极性。

　　追溯到我的祖上三代，他们都是只穿得起半截裤的农民，理所当然是贫农成分。但我自己大学毕业后在城市里做了房奴，自然不能算作无产阶级，至少也是个“贫农家庭”出身的“干部”兼小资产阶级、知识分子。

　　个人成分问题似乎解决了，还有一个家庭成分问题呢。于是问问夫人的家庭成分，爷爷竟然是“地主”，外公竟然是“资产阶级”！