states of South-West Nigeria. Locations were defined by drawing a 2-mile radius around each screening center where the intervention was implemented, and randomly selecting households within this radius.<sup>7</sup> We ensured that there were buffer zones between communities to minimize the risk of contamination across study groups. These locations constitute our unit of randomization. Online Appendix A describes the selection of locations and respondents in detail, and Appendix Figure A1 shows the geographic distribution of treatment and control locations.

To identify study participants, we adopted a three-step recruitment strategy. First, enumerators visited a random selection of 200 − 225 households per location. Second, the research team randomly selected one person aged 18 to 25 in each household to be invited to an initial film screening, which we denote as Screening 0. This film was different from MTV Shuga as the intent was to recruit amongst people available to attend film screenings during weekends, so as to reduce attrition. The selection was stratified by gender, half males and half females. Out of 17, 224 people invited to Screening 0, 6, 613 attended, with a turnout rate of 38.4 percent. Appendix Table A1 compares those who chose to attend Screening 0 and those who did not, on a number of socioeconomic characteristics. The two samples are well balanced; a few variables show significant differences, yet of extremely small magnitude: in all cases the normalized difference is below the threshold of 0.25 suggested by Imbens and Rubin (2015). We thus conclude that those who attended Screening 0 were a representative subset of the households invited.<sup>8</sup> The third step was the selection of our baseline sample. In each location enumerators randomly selected 64 individuals among those who attended Screening 0 and visited them at home to administer the baseline survey. From now on, we refer to these 64 individuals as ‘main study participants’.<sup>9</sup> At the end of the survey, the main study participants received invitations to attend two other screenings organized in the two weekends following the interview: Screenings 1 and 2. Those in the ‘Friends treatment’(to be described in the next section) also received invitations to bring up to two friends of their choice. Note that invitees were not told in advance what they would watch, neither before Screening 0 nor before Screening 1.

Attendance to the screenings was relatively high: 78.4 percent of those invited attended at least one of the two screenings, with the shares being 77 percent in the treatment group and 81 in the control group (significantly different).<sup>10</sup> Note that in all our analysis we report

> 7 The condition for a household to be in the study was that at least one of the members should be in the target age range of our intervention, i.e., 18-25 years old.

> 8 We also compared our sample to the 2008 Nigeria DHS, restricted to the South-Western region, and found that the two were quite similar in terms of religion (a third Muslim and two thirds Christian), years of education (around 11 years) and television-ownership rates (around 90 percent).

> 9 Appendix Table A2 shows balance in observable characteristics between the people who attended Screening 0 and were selected into the baseline sample and those that were not.

> 10 70.5 percent of our sample attended Screening 1, 57.2 attended Screening 2, and 49.4 percent attended both. The likelihood of attending Screening 2 conditional on attending Screening 1 is 70 percent in both treatment and control.

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