A Social or Development Impact Bond (SIB or DIB) is a pay-for-results funding model involving multiple parties. It is designed to enable non-profit interventions (typically encouraged by public actors) to attract private investment in order to pre-finance the activities needed to generate a defined set of impact outcomes (outcome targets). Private investors provide the up-front capital. The impact bond reimburses the investors for their capital with a pre-defined return in case the outcomes targets are achieved. The transaction may be structured with a Special Purpose Vehicle (SPV) which acts as a contract partner for all actors involved. In this case the SPV takes on the private capital from the investors and contracts one or more service providers who are charged with actually generating the outcomes. The service providers are usually NGOs. There is typically an independent organisation involved for verification of the impact outcomes. An impact bond is not a bond in the traditional sense of the word, since the repayment and the return are dependent on the achievement of desired outcomes. In case the outcomes target is not met, the investors typically receive neither a return nor the (full) repayment of the principal.