A toric variety is, roughly speaking, a complex algebraic variety which is the (partial) compactification of an algebraic torus T C = (C * ) r . It admits (by definition) an action of T C such that, for some point * ∈ X, the orbit of * is an embedded copy of T C . The most significant property of a toric variety is the fact that it is characterized entirely by a combinatorial object, namely its fan, which is a collection of convex cones in R r . As a general reference for the theory of toric varieties we use [Od1], together with the recent lecture notes [Fu].In this paper we shall study the space of rational curves on a compact toric variety X. We shall obtain a configuration space description of the space Hol(S 2 , X) of all holomorphic (equivalently, algebraic) maps from the Riemann sphere S 2 = C ∪ ∞ to X. Our main application of this concerns fixed components Hol * D (S 2 , X) of Hol * (S 2 , X), where the symbol D will be explained later, and where the asterisk indicates that the maps are required to satisfy the condition f (∞) = * . If Map * D (S 2 , X) denotes the corresponding space of continuous maps, we shall show that the inclusioninduces isomorphisms of homotopy groups up to some dimension n(D), and we shall give a procedure for computing n(D).A theorem of this type was proved in the case X = CP n by Segal ([Se]), and indeed that theorem provided the motivation for the present work. Our main idea is that the result of Segal may be interpreted as a result about configurations of distinct points in C which have labels in a certain partial monoid. We shall show that Hol * D (S 2 , X) may be identified with a space Q X D (C) of configurations of distinct points in C which have labels in a partial monoid M X , where M X is derived from the fan of X. Then we shall extend Segal's method so that it applies to this situation.A feature of the method is the idea that the functor U → π i Q X D (U ) resembles a homology theory. This functor has some similarities with the Lawson homology functor introduced in 1991 Mathematics Subject Classification. 55P99, 14M25.