[Bahasa]: Penelitian ini bertujuan untuk menghasilkan model Problem Based Learning (PBL) menggunakan penilaian Assessment for Learning (AfL) berbantuan smartphone, disingkat PBL-AfL-S yang valid, praktis dan efektif untuk mendukung implementasi kurikulum 2013 di SMA. Tahap-tahap pengembangan model PBL-AfL-S terdiri dari penelitian pendahuluan, pengembangan/prototiping, dan evaluasi. Kualitas model PBL-AfL-S mengacu pada kriteria kualitas menurut Nieveen (1999) yaitu valid, praktis, dan efektif. Model PBL-AfL-S diujicobakan di SMA Negeri 3 Klaten dalam dua tahap uji coba. Uji coba tahap I dilaksanakan di kelas XI-IPA 6 dan uji coba tahap II dilaksanakan di kelas XI-IPA 7. Instrumen penelitian terdiri dari: 1) Instrumen penilaian kevalidan komponen model dan perangkat pendukung pembelajaran, 2) Instrumen kepraktisan aktivitas guru dan siswa, dan 3) Instrumen keefektifan yang meliputi angket penilaian diri, lembar penilaian proyek, tes prestasi belajar, dan lembar respon siswa. Hasil penelitian menunjukkan bahwa model PBL-AfL-S dan perangkat pembelajarannya telah memenuhi kriteria valid, praktis dan efektif. Kata kunci: Pembelajaran; Masalah; Asesmen; Smartphone [English]: This study aims to develop a Problem Based Learning (PBL) model using Assessment for Learning (AFL) with smartphone, abbreviated as PBL-AfL-S as valid, practical and effective to support the implementation of the 2013 curriculum in High School. The stages of developing the PBL-AfL-S model consist of preliminary research, development or prototyping, and evaluation. The quality criteria of PBL-AfL-S refer to Nieveen (1999), i.e. valid, practical, and effective. The PBL-AfL-S model was piloted in SMA Negeri 3 Klaten in two phases. Tryout 1 was conducted in class XI-IPA 6 and tryout 2 was in class XI-IPA 7. The research instruments consist of: 1) The validity instrument of the model and its learning support tools, 2) the practicality of the teacher’s and students’ activity, and 3) The effectiveness instruments including self-assessment questionnaires, project appraisal sheets, achievement tests, and student response sheets. The results show that the PBL-AfL-S model and learning tools have met the valid, practical and effective criteria. Keywords: Problem based Learning, Assessment; Smartphone