Positive screening is the term applied to the
practice of
attaining
stock ownership in
corporations which fall in line with your personal
values.
Positive screening is a tactic to seek out companies that DO have desired policies rather than those that DO NOT have undesired policies; see negative screening.
The most frequently sought out policies include social contributions, environmental awareness, and corporate responsibility. Depending on the interest of the investor, one may hear requests for businesses which adopt environmentally progressive standards, are cooperatively or employee-owned, which have affirmative action plans, or that provide equal opportunity for women, youth, persons of non-dominant ethnicity, the elderly, etc.
Purchasing stocks through an ethical filter shows, through the results, the value choices made by a given investor. A wise prince would make his public stocks visibly "ethical", but use whatever means he should deem most effective to garner capital. The argument, however, for actually investing in ethical companies (despite perhaps lower growth rates), is that these companies are usually quite sustainable, and that they are a growing industry, and will continue to be as long as the world continues to consume.