In this paper, we determine the partition dimension of a complete multipartite graph \( K_{n_1, n_2, \ldots, n_r} \), namely \( pd(K_{n_1, n_2, \ldots, n_r}) \). We show that \( pd(K_{n_1, n_2, \ldots, n_r}) = r + n – 1 \) if \( n_i = n \) for \( 1 \leq i \leq r \), and \( pd(K_{n_1, n_2, \ldots, n_r}) = r + n – 2 \) for \( n = n_1 \geq n_2 \geq \ldots \geq n_r \). We also show that the partition dimension of the caterpillar graph \( C_n^m \) is \( m \) for \( n \leq m \) and \( m + 1 \) for \( n > m \), and the partition dimension of the windmill graph \( W_{2}^{n} \) is \( k \), where \( k \) is the smallest integer such that \( \binom{k}{2} \geq m \).