Interleaved composites have shown promise in altering the failure mode(s) of composites and offer a facile approach to modify traditional carbon fibre reinforced composites (CFRCs). The addition of thermoplastics has been shown to enable easy repair [1], as well as controlled alteration of the stiffness upon heating [2]. The addition of a tough thermoplastic interleave in a CFRC is expected to improve shear properties in tension in matrix dominated failures/configurations [3]. Pre-cut unidirectional carbon fibre prepreg (M21/194/34%/T800S) composites were tested in tension with a 20 mm overlapped finger joint architectures, following previous methodology [4]. In between the overlapping finger jointed region the effect of introducing polyethersulfone (PES) interleave film is investigated. The PES interleave spans 10 mm, centrally, within this overlapped region. All of the carbon fibres in the finger joint arrangement were cut, such that no fibre(s) span the full length of any sample. The properties arising from these configurations are therefore strongly dependent on the interply overlap regions. Samples with the addition of a thick PES interleave arrested the initial crack which formed at the pre-cut site. The strain to-failure of the thick PES interleaved samples was over 3.2%, an increase of 85% compared to the baseline samples, and catastrophic failure was delayed in the majority of instances. The specific use of this embodiment could be to toughen regions in composites which require the overlap of prepregs and with further developments the approach could be exploited to yield a high performance yet (pseudo)ductile response under tension. [1] P. Robinson, 17th ECCM, Munich 2016, ISBN 978-3-00-053387-7 [2] H. A. Maples, Compos. Sci. Technol., 128 (2016), DOI:10.1016/j.compscitech.2016.03.028 [3] G. Grail, Compos. Sci. Technol., 106 (2015), DOI:10.1016/j.compscitech.2014.11.006 [4] G. Czél, Compos. Sci. Technol., 106 (2015), DOI:10.1016/j.compscitech.2014.10.022