The investigators propose to conduct a randomized controlled trial in collaboration with the Fundacion Raices, a non-governmental organization (NGO) with strong ties to the local community of Esmeraldas, Ecuador. A total of about 3,000 subjects will be involved in the full-scale study over the course of 2 years. In partnership with the Fundacion Raices, the research team will set up stands at four public places in the city of Esmeraldas: the "malecon" (esplanade on the town's waterfront), the "Centro Comercial Multiplaza" (Esmeraldas' large shopping mall), the municipal market (a popular destination for groceries, etc.), and a public park located in the city center. Each stand will feature a sign inviting individuals to stop and "get their health checked", and will provide free refreshments (juice boxes and water). A monitor will approach individuals at the malecon/shopping center/municipal market/public park and ask whether they are interested to learn about a health initiative by the Fundacion Raices and a group of public health researchers. If an individual expresses interest, a field worker will begin the three steps of the experiment: (1) The participant completes a brief, anonymous survey with demographics, socio- economic, and past HIV/AIDS testing information. (2) The participant receives the script and actions associated with the assigned randomized experimental condition. There are three experimental conditions: - T1 = "Information". T2 = "Active Choice". T3 = "Monetary incentive". (3) Whether the participant shows up at the medical facility to get tested is entered in the record.

Randomization: The randomization will vary by week (i.e., all participants who present on the same week will be assigned to the same experimental condition) to minimize spillover effects due to communication between participants assigned to different groups, and to avoid confusion among the field staff.

The implementation schedule will be designed to guarantee balance of treatment conditions across locations and days of the week. To provide the participants with privacy when filling the questionnaire, after the initial approach, the interaction between the participants and field staff will occur in a booth next to the desk which will obscure the participant from the view of others. Participants will be read a statement inviting participation; description of privacy protection measures; and solicitation of verbal consent.

The investigators also plan to test our experimental conditions with subjects from high-risk population groups. For high-risk population groups, the investigators will rely on the previous experience of research team members in which Female Sex Workers (FSWs) and Men who have Sex with Men (MSM) were contacted through the official registry and local MSM association, respectively. A similar approach will be used in this project. Participants in these high-risk groups will be approached individually by field staff, after having been randomly assigned to one of three experimental conditions. Participants will be read a statement inviting participation; description of privacy protection measures; and solicitation of verbal consent. The investigators expect to include about 1,000 subjects from the high-risk populations.

The medical testing facility where participants will go is "Microlab - Laboratiorio Clinico Bacteriologico", centrally located in Esmeraldas (across the street from the Delfina Torres Public Hospital). It is a private facility staffed by healthcare professionals connected to the testing lab at the Medical School and Hospital of the Universidad San Francisco de Quito (USFQ) in Quito, Ecuador. Blood samples will be tested using standardized commercially available HIV testing kits. Participants in the financial incentive condition will receive their reward from the staff at the Microlab in Esmeraldas. The participants will not provide names to the lab personnel. Instead, they will give them the second portion of the registration card, which indicates their study identification number (ID). The lab staff will write the study ID onto the sample collection label. Blood samples will be sent to the testing facility at the USFQ. There, trained laboratory personnel will conduct the HIV screening test following Standard Operating Procedures. After conducting the test, laboratory personnel will record the results in an excel spreadsheet using the participant's ID number as identifier (i.e., there will be no record of name or other personal identifiable information).

Afterwards, the results will be individually printed on a pre-designed "HIV screening Test Results" Form. Individual results will be put in an envelope. Envelopes will be sealed and sent back to the testing facility in Esmeraldas via a private carrier. After arrival, results will be archived in a locked unit and delivered to participants as they arrive to claim their results. Participants will receive their results in a timely manner, according to local health policies. HIV positive individuals will be encouraged to visit the local health district to enroll into the national HIV/AIDS program for treatment.