The improvement of writing skills is one of the aims of the educational system. The present study implemented strategy-focused instruction through the Cognitive Self-Regulation Instruction (CSRI) program which included three instructional components: Direct Teaching, Modelling, and Peer-Practice. The aim was to explore the short- and long-term effects of different sequences of the three CSRI instructional components on writing skills (reflected in greater Coherence, Structure and Quality of the text product). Six 4th grade primary education classes from three different schools (N = 126) were randomly allocated to the experimental conditions which differed in the order in which the instructional components were implemented: Direct Teaching, Peer-Practice, and Modelling (experimental condition 1, n = 47); or Modelling, Peer-Practice, and Direct Teaching (experimental condition 2, n = 36). A control condition (n = 43) was also included in which students received traditional instruction. Writing performance was measured through compare-contrast writing tasks. In addition, writing performance was assessed through the anchor text procedure (considering three variables: Coherence, Structure and Quality). Findings supported the effectiveness of strategy-focused instruction after four sessions of the CSRI program. Experimental conditions 1 and 2 showed a significant gain relative to the control condition and were equally effective for the improvement of writing skills over a short-term period. More specifically, the Peer-Practice component was associated with the largest gains in the 4th grade students' writing skills.