This guideline note covers one category of AFI’s Second Tier Set of Financial Inclusion Indicators, developed jointly by AFI’s Mobile Financial Services Working Group (MFSWG) and Financial Inclusion Data Working Group (FIDWG) as a tool for measuring access and usage of mobile financial services. The Second Tier Set of Indicators are a broader set of financial inclusion indicators considered important but not ‘core’, which are being developed to allow policymakers to select the most useful indicators for their particular country context and level of development.