Can I claim MY elderly Mother-in-Law on My 2007 taxes


:)

We need a bit more information to be able to answer your question:

Are you filing as Married Filing Jointly?
Did you provide more than 50% of your mother-in-law's support?
Is her gross income less than $3,400?
Is she a US citizen or resident alien, or resident of either Mexico or Canada?

See Pub 501 for all the rules regarding whom you can claim as a dependent:
http://www.irs.gov/pub/irs-pdf/p501.pdf