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How can I invest in an index fund but screen out (remove) certain categories of socially irresponsible investments?
You could certainly look at the holdings of index funds and choose index funds that meet your qualifications.  Funds allow you to see their holdings, and in most cases you can tell from the description whether certain companies would qualify for their fund or not based on that description - particularly if you have a small set of companies that would be problems. You could also pick a fund category that is industry-specific. I invest in part in a Healthcare-focused fund, for example.  Pick a few industries that are relatively diverse from each other in terms of topics, but are still specific in terms of industry - a healthcare fund, a commodities fund, an REIT fund.  Then you could be confident that they weren't investing in defense contractors or big banks or whatever you object to. However, if you don't feel like you know enough to filter on your own, and want the diversity from non-industry-specific funds, your best option is likely a 'socially screened' fund like VFTSX is likely your best option; given there are many similar funds in that area, you might simply pick the one that is most similar to you in philosophy.