The study of Islamic finance would not be complete without a thorough understanding of the core Islamic injunction on ribā an-nasi’ah that underlies current financial exchanges. However, several studies purport Muslim economic woes to be linked to the rigidities of this injunction. By employing a capital structure model in a rational expectations setting, we justify this religious injunction is in fact welfare-enhancing. This is because it averts: (i) economically inefficient financing structures; (ii) non-sustainable long-run equilibria stemming from the expropriation of wealth; (iii) fragile financial systems; and (iv) financial exclusion. We then present in this study a perspective of a quasi-equity financing tool to calibrate the Islamic financial system. Lastly, we attribute Muslim economic underdevelopment to weak-form property rights and lack of Islamic rulings (ijtihad) in the production of new financial instruments, institutions and markets. The ensuing studies in this collection of Islamic finance essays draws from the above foundational research. Specifically, our second study contrasts an interest-free payday loan facility with interest-based schemes of mainstream credit and current payday loans. An examination of alternative form of credit facility is timely as inefficiencies in mainstream credit markets have pushed selected households to frequent high cost payday loans for their liquidity needs. Ironically, despite the prohibitive cost there is still persistent demand for the product. This paper rides on the public policy objective of expanding affordable credit to rationed households. Here, we expound a simple model that integrates inexpensive interestfree liquidity facility within an endogenous leverage circuit. This builds on the technology of Rotating and Savings Credit Association/ Accumulating Savings and Credit Association/ mutual/ financial cooperative and cultural beliefs indoctrinated in Islam. Our results indicate the potential economic efficiency of this interest-free circuit in contrast to the competing interest-bearing schemes of payday lenders and mainstream financiers. A version of this essay co-authored with M.S. Ebrahim and A. Jaafar has been accepted in the forthcoming Journal of Economic Organization and Behaviour. The unravelling of the recent crisis underscores the pertinence of proper loan pricing that strips away the put option to default, particularly where there is extensive churning of the collateral in the financial system. This survey paper, the third in our collection of essays, explores this issue from an agency theoretic perspective of trading financial claims between risk-averse lender and borrower, in rational expectations and symmetric information setting. Constructing on lender (financial intermediary) asset transformation and public depositor custodial functions, we intuitively deduce the economic efficiency of pragmatically default free solution over default-prone one. By enforcing proper structuring of the former, it averts financial fragility and costly bailouts. Furthermore, it endows depositors with similar security of deposit insurance scheme without the associate moral hazard issues. Finally, we detail design of this pragmatically default-free structure that reduces in-moneyness of the put option to default.