We assessed the feasibility and acceptability of using text messages to monitor and encourage physical activity in the first 21 participants enrolled in an ongoing randomized controlled trial evaluating a 16-week Short Message Service/Multimedia Message Service (SMS/MMS) intervention (iSTEP) designed to increase moderate physical activity and improve neurocognition in persons with HIV-associated neurocognitive disorders (HAND; iSTEP, n = 11; control group, n = 10). Data were collected during the intervention and from interviews conducted at the 16-week postintervention visits. Text message response rates for both iSTEP and control participants were high (89% and 85%, respectively). Pedometer self-monitoring, step count goals, and milestone achievement texts were reported to facilitate physical activity. All iSTEP participants (100%) and 70% of control participants indicated that they would recommend the study to other people living with HIV. The results indicate that it is feasible to administer an SMS/MMS physical activity intervention to persons with HAND.