Spousal Contribution to an IRA
In the United States, spousal contributions can be made to a traditional IRA if either party has income.
In 2013, each person can contribute $5,500/year (or $11,000/year as a couple) to a qualified traditional IRA. Additionally, if you (and/or your spouse) are over 50, you can make what are called "catch-up contributions" (an extra $1,000 per person per year for each individual over 50).
As such, if either member of the combined couple is eligible, contributions on behalf of the non-working spouse can be made using marital income. If one party is excluded, the other party may still eligible.
In some cases, there may be a maximum amount of income that you can earn and still be eligible. If the couple has taxable income that does not exceed the phaseout threshold ($178,000/year in 2013), that couple can contribute to a traditional IRA.
If the couple's income exceeds the threshold, then it is still possible to make contributions, but they will not be deductible. As such, converting the balance to a Roth makes sense. As always, consult your account to ensure that your situation applies.