Abstract. A spanning tree that simultaneously approximates a shortest-path tree and a minimum spanning tree is called a shallow-light tree (shortly, SLT). More specifically, an (α, β)-SLT of a weighted undirected graph G = (V, E, w) with respect to a designated vertex rt ∈ V is a spanning tree of G with: (1) root-stretch α -it preserves all distances between rt and the other vertices up to a factor of α, and (2) lightness β -it has weight at most β times the weight of a minimum spanning tree M ST (G) of G. In this paper we show that Steiner points lead to a quadratic improvement in Euclidean SLTs, by presenting a construction of Euclidean Steiner (1 + , O( 1 ))-SLTs in arbitrary 2-dimensional Euclidean spaces. The lightness bound β = O( 1 ) of our construction is optimal up to a constant. The runtime of our construction, and thus the number of Steiner points used, are bounded by O(n).