American Capital Strategies Ltd has invested $31 million in children's apparel wholesaler and retailer Hartstrings Inc. The finance will be used to partially finance the asset Hartstrings' acquisition by Keystone Holdings LLC. Hartstrings is a designer, wholesaler and retailer of classic coordinated children's apparel sold under the hartstrings, kitestrings and kc parker labels. American Capital is funding a senior term loan, senior revolving credit bridge facility and a subordinated note with warrants.