This toolkit was drafted to support UNFPA offices in designing country investment cases in support of one or more of UNFPA's people-centred transformative results: ending preventable maternal mortality; ending the unmet need for family planning; and ending gender-based violence (GBV) and harmful practices including female genital mutilation (FGM) and child, early and forced marriage. Conceived as a concise and practical guide, it includes tools for: preparing for an investment case; estimating the cost of the investment; developing investment scenarios to determine the scale of the investment's impact; framing the investment angle; and using the investment case in national advocacy efforts.