Costing is the process of data collection and analysis for estimating the cost of a health intervention. High-quality cost data on SBC are critical not only for developing budgets, planning, and assessing program proposals, but can also feed into advocacy, program prioritization, and agenda setting. To better serve these data needs, these guidelines aim to increase the quantity and quality of SBC costing information. By encouraging cost analysts to use a standardized approach based on widely accepted methodological principles, we expect the SBC Costing Guidelines to result in well-designed studies that measure cost at the outset, to allow assessment of cost-effectiveness and benefit-cost ratios1 for SBC programming. Such analyses could also potentially help advocates for SBC to better make the case for greater investment in SBC programming.2 These guidelines lay out a consistent set of methodological principles that reflect best practice and that can underpin any SBC costing effort.