Modern microfinance models date back to the 1970s when experimental programs in Bangladesh, Brazil, and a few other countries began to extend tiny loans to groups of poor women to invest in microenterprises. By lending to groups of women where every member of the group guaranteed the repayment of all members, these microcredit programs challenged the prevailing conventional wisdom and proved that poor people without collateral could be "creditworthy". When offered the opportunity, they would repay loans with interest, at extraordinary rates of repayment. A lecture with Lin Lerpold, Assistant Professor at the Stockholm Scool of Economics and a member of the Sustainability Research Group.