Welcome to the latest installment of our weekly fund review, in which we peruse the past week's notable fund news and tell you what it means for Foolish investors.

Social responsibility on the rise
Socially responsible investing is getting a boost from investors' 401(k) plans. More retirement plans are adding these funds to their menus, usually at plan participants' request. A few such funds have reported healthy asset growth as a result, including the Vanguard FTSE Social Index Fund (VFTSX), the Neuberger Berman Socially Responsible Fund (NBSRX), and the TIAA-CREF Social Choice Equity Fund (TISCX).

Vanguard's fund, which counts Microsoft (NASDAQ:MSFT), Bank of America (NYSE:BAC), and Cisco Systems (NASDAQ:CSCO) among its carefully screened holdings, reported that its inflows in the first four months of 2007 doubled those from the same period last year.

I've got no problem with 401(k) plans that offer more ethical options to their participants, but Fools shouldn't assume that investing in them is necessarily the smartest move. This is your retirement money -- your future -- on the line. Do you want to invest it in the best mutual fund you can find, or in a socially responsible fund that might be mediocre at best?

Don't buy a socially screened fund for the feel-good factor alone. Evaluate the fund on its own merits; if it measures up, invest away. But if it falls short, find a better place to invest your money, and consider volunteering a few hours a week for the cause of your choice. That way, you can do good works without penalizing your retirement money.

State Street enters the bond ETF space
This week, State Street Global Advisors added its voice to the chorus by rolling out its first five fixed-income exchange-traded funds. Trading since Wednesday, these five ETFs carry State Street's SPDR tag, and range from a one-to-three-month T-bill fund to a long-term Treasury fund. With this addition, State Street joins Barclays Global Investors and Vanguard in the relatively new competition for bond ETF assets.

If you're interested in a fixed-income ETF, make sure you've got solid reasons for choosing one over an actively managed or indexed bond mutual fund. If you want trading flexibility, or plan on making frequent trades in an attempt to time the market, reconsider buying that ETF. Most investors should use fixed-income securities to dampen overall portfolio volatility and protect principal, not to make a quick buck or two. Firms like State Street are now giving investors the tools to easily and cheaply use bond ETFs. Just make sure you don't abuse them.

Chart-topping inflows for international funds
New data from the Investment Company Institute shows that inflows into mutual funds during April more than doubled those in March. According to ICI, investors added roughly $18.3 billion to equity funds in April, compared to $8.1 billion in March. Of April's gains, approximately $16.6 billion went to world equity funds, which do the bulk of their investing abroad. Foreign funds have grown particularly popular lately, as their red-hot returns boost investors' portfolios.

It's not surprising that international markets' strong showing has investors flocking to global funds. Many otherwise smart investors are very reactive thinkers. Foreign markets have delivered outstanding returns, but some, especially emerging markets, now look increasingly speculative. The odds suggest that international stocks' heady gains may not continue much longer. Investing in them now in hopes of a quick profit is a losing strategy.

On the other hand, long-term investors should always have at least some international exposure, so there's no need to run away. Just don't pile huge amounts of money into foreign funds now because they've done well, or because everyone else is doing it. Stay sensible, and odds are you'll come out ahead.

Further fund-amental Foolishness:

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Fool contributor Amanda Kish lives in Rochester, N.Y., and does not own shares of any of the companies or funds mentioned herein. Microsoft is an Inside Value recommendation, while Bank of America is an Income Investor pick. The Fool's disclosure policy marches to the beat of its own drummer.