Investing isn't easy. Even Warren Buffett counsels that most investors should invest in a low-cost index like the S&P 500. That way, "you'll be buying into a wonderful industry, which in effect is all of American industry," he says.

But there are, of course, companies whose long-term fortunes differ substantially from the index. In this series, we look at how members of the S&P 500 have performed compared with the index itself.

Step on up, Kimberly-Clark (NYSE: KMB).

Kimberly-Clark shares have crushed the S&P 500 over the last three decades:

Source: S&P Capital IQ.

Since 1980, shares have returned an average of 15.4% a year, compared with 11.1% a year for the S&P (both include dividends). One thousand dollars invested in the S&P in 1980 would be worth $29,400 today. In Kimberly-Clark, it'd be worth $96,700.

Dividends accounted for a lot of those gains. Compounded since 1980, dividends have made up about two-thirds of Kimberly-Clark's total returns. For the S&P, dividends account for 41.5% of total returns.

Now have a look at how Kimberly-Clark earnings compared with S&P 500 earnings:

Source: S&P Capital IQ.

Pretty average. Since 1995, earnings per share have grown by an average of 5.5% a year, compared with 6% a year for the broader index.

What's that meant for valuations? Not much. Kimberly-Clark has traded for an average of 19 times earnings since 1980 -- about the same as the 21 times earnings for the broader S&P 500.

Through it all, shares have been solid outperformers over the last three decades.  

Of course, the important question is whether that will continue. That's where you come in. Our CAPS community currently ranks Kimberly-Clark with a five-star rating (out of five). Do you disagree? Leave your thoughts in the comment section below, or add Kimberly-Clark to My Watchlist.