The goal of this clinical trial is to learn if an interactive mHealth intervention will be effective in helping HIV-positive women in high-burden settings who are initiating antiretroviral therapy (ART) take their ART regularly as prescribed, effectively reducing their viral load. The main question it aims to answer is:

- Compared to standard of care, will Motivation Matters! (MM!) be significantly more effective at achieving undetectable viral load in women with HIV by month six.

Researchers will compare the undetectable HIV viral load in women who receive individualized text messages (intervention group) in addition to standard care to those who receive standard care alone (control group).

Participants in the intervention group will receive three messages per week in month one, then two messages per week for the six-month intervention period. Participants will be asked to send a brief, standardized reply to each message, indicating that they are doing well or that they have a question or problem. Regardless of study arm, women will receive ART and counseling consistent with Kenyan guidelines.

Inclusion Criteria:

• Age >18
• Transactional sex in past 12 months
• HIV-positive
• Not currently on ART
• Enrolled in one of the Sex Workers Outreach Program clinics
• Has access to mobile phone
• Willing to receive study text messages
• Able to read or have someone else read

Exclusion Criteria:

• Plans to move away in next 6 months
• Undetectable viral load at baseline
• Pregnant