This study describes the development and initial validation of the Self-regulated Learning in Primary Education Scale (SRLIPES). This instrument was designed to measure the self-regulated learning strategies in primary school children's learning processes on-line. Essentially, the aim was to create an instrument based on Zimmerman's triadic model of Self-regulated Learning (SRL) with three distinct phases, the forethought phase, the performance phase and the reflection phase. Exploratory (n = 432) and confirmatory factor analysis (n = 255) allowed us to validate a two factor scale (the forethought phase and the performance/reflection phase). This scale presents good measurement qualities [χ2 = 201.034, df = 146, p = .002, χ2/df = 1.377, CFI = .940, IFI = .941, RMSEA = .039 (LO=.024, HI=.051), SRMR = .050, AIC = 286.034], is an effective tool to measure SRL in primary school children and provides a deeper understanding of children's perception of their own learning.