NPLs have detrimental effects on the financial performance of the banks, which eventually influence the economies. NPLs have forward and backward relationship with macroeconomic and microeconomic determinants. These determinants not only influence NPL ratios, but high NPL ratios also significantly impact them. The present chapter critically examined the relationship between NPLs and macroeconomic and microeconomic determinants. It also thoroughly examined the role of regulatory and supervisory authorities in addressing the problem of NPLs in the UK, India, and Ireland. The researcher analysed the crucial acts, statutes, regulations, directives, circulars, Basel guidelines, case law, etc., dealing with financial sectors, including banks. A comparative analysis of the regulatory, policy and supervisory measures of the UK, India and Ireland provided insight into the approaches adopted by an advanced jurisdiction--the UK, an emerging nation, India, and an EU Member State badly hit by the rising level of NPLs after the GFC--Ireland. This chapter effectively concludes the issue discussed in the book, besides suggesting some useful interventions for implementation.