CONTEXT: The World Health Organization (WHO) has developed a decision-making tool to be used by providers and clients during family planning visits to improve the quality of services. It is important to examine the tool's usability and its impact on counseling and decision-making processes during family planning consultations. METHODS: Thirteen providers in Mexico City were videotaped with family planning clients three months before and one month after attending a training session on the WHO decision-making tool. The videotapes were coded for client-provider communication and eye contact, and decision-making behaviors were rated. In-depth interviews and focus group discussions explored clients' and providers' opinions of the tool. RESULTS: After providers began using the decision-making tool, they gave clients more information on family planning, tailored that information more closely to clients' situations and more often discussed HIV/AIDS prevention, dual protection and condom use. Client involvement in the decision-making process and client active communication increased, contributing to a shift from provider-dominated to shared decision making. Clients reported that the tool helped them understand the provider's explanations and made them feel more comfortable talking and asking questions during consultations. After one month of practice with the decision-making tool, most providers felt comfortable with it and found it useful; however, they recommended some changes to the tool to help engage clients in the decision-making process. CONCLUSIONS: The decision-making tool was useful both as a job aid for providers and as a decision aid for clients.