Introduction: Studies have found that breastfeeding problems are associated with negative breastfeeding outcomes. Unfortunately, assessing breastfeeding problems can be quite difficult. The objective of the paper is to share the process of tool development for the assessment of breastfeeding problem in an Indonesian setting. Methods: The development of the tool was a two-stage process, consisting of understanding the range and pattern of breastfeeding problems (through literature review, discussions with lactation experts, and in-depth interviews with nursing mothers) and the production of the tool (through discussions with graphic designers and communication practitioners, pre-testing the tools, and finalising a workable, viable tool). The process led the authors to use flash cards for assessing the breastfeeding problems. Each card consisted of information about age, a code number, an image and a description of the breastfeeding problem. Each set of the flash cards represented an age period of 0-1, 1-3, and 3-6 months. The final flash cards were used in a cross-sectional study of 205 mothers of infants aged 6-12 months in Maros District, South Sulawesi. Results: The flash cards captured patterns of breastfeeding problems experienced by mothers within the first month, such as sore nipple, no milk production, fatigue, breast engorgement, and sleepy baby, or those problems that persisted throughout the six-month period such as infants' refusal to breastfeed and mothers feeling fatigued. The decreasing or increasing magnitude of a problem over time was also reflected in the flash cards. Conclusion: Identification of the dynamic patterns and magnitude of breastfeeding problems was successfully captured with the use of flash cards.