Research has shown that mobile phone contraceptive behavioral interventions can increase knowledge and use of contraception, but other studies have failed to demonstrate a beneficial effect. The objective of this trial was to estimate the effect of a contraceptive behavioral intervention delivered by mobile phone text message on young Palestinian women's attitudes towards effective contraception.We conducted a randomized controlled trial among women aged 18-24 years living in the West Bank, who were not using an effective method of contraception. The intervention group received zero to three messages per day (113 messages for female-not married and 120 messages for female-married) for 120 days. The control group received 16 messages over 120 days about trial participation. The primary outcome was acceptability of at least one method of effective contraception at 4 months. Secondary outcomes were use of effective contraception at 4 months and any use during the study, acceptability of individual methods, service uptake, unintended pregnancy and abortion. Process outcomes included knowledge, perceived norms, personal agency and intention. All outcomes were self-reported. We analyzed the outcomes using logistic and linear regression.A total of 578 participants were enrolled and 464 (80%) completed follow up at 4 months. Intervention group participants were more likely to find at least one method of effective contraception acceptable (31% in the intervention group versus 17% in the control group, adjusted OR 2.34, 95% CI 1.48-3.68, p < 0.001). They had a higher mean knowledge score, were more likely to find the intrauterine device, injection, implant and patch acceptable, to agree that their friends would use an effective method and to intend to use an effective method, compared to participants in the control group. While in the direction of intervention benefit, there were no differences between the groups in the use of effective contraception at 4 months and any use during the study, pill acceptability, service uptake, unintended pregnancy and induced abortion.The intervention can improve attitudes, knowledge-perceived norms and intention to use effective contraception among young women in Palestine. Research is needed to evaluate the efficacy of the intervention for contraceptive behavioral outcomes in Palestine.ClinicalTrials.gov, NCT02905461 . Registered on 14 September 2016. World Health Organization Trial Registration Data Set: http://apps.who.int/trialsearch/Trial2.aspx?TrialID=NCT02905461.