We extend the Caffarelli-Córdoba estimates to the vector case (L. Caffarelli and A. Córdoba, Uniform Convergence of a singular perturbation problem, Comm. Pure Appl. Math. 48 (1995)). In particular, we establish lower codimension density estimates. These are useful for studying the hierarchical structure of minimal solutions. We also give applications.2010 Mathematics Subject Classification. 35J20, 35J47, 35J50.(c) the phase separation system ∆u i − j =i u i u j = 0, i = 1, . . . , m (Caffarelli and Lin [15]) and its variants. All these systems are included in the general framework of Rubinstein, Sternberg and Keller [27], [28].We assumewhere · denotes the Euclidean inner product in R m and | · | the associated norm.In the present paper we limit ourselves to uniformly bounded solutions to (1.1) that are minimal with respect to their boundary conditions (called minimizers by some authors),2 0 (Ω; R m ) (1.6) for every open bounded set Ω ⊂ D. Moreover we assume |u − a| < M, |∇u| < M, on R n .(1.7)The basic estimate for minimal solutions (cr. Lemma 2.1) isWe generally omit the center and write it B R . In this paper, we give two different extensions of the Caffarelli-Cordoba density estimates [14] to the vector case, together with a few applications. In the scalar case, among other things, these estimates refine the linking of the phase transition model to minimal surfaces and have played a major role in the resolution of the De Giorgi conjecture in higher dimensions (Savin [29]). Other extensions of the density estimates in different contexts have been provided by Farina and Valdinoci [20], Savin and Valdinoci [30],[31], Sire and Valdinoci [32], and very recently by Cesaroni, Muratov and Novaga [16].We denote L k the k-dimensional Lebesgue measure and let