The paper examines isoclinism classes of \(p\)-groups [as introduced by Ph. Hall in J. Reine Angew. Math. 182, 130-141 (1940; Zbl 0023.21001)] from the perspective of group enumeration. Let \(p\) be a prime. Define \(f_ \Phi (p^ m)\) to be the number of (isomorphism classes of) groups of order \(p^ m\) in an isoclinism class \(\Phi\). Define \(F(p^ m)\) to be the maximum value of \(f_ \Phi (p^ m)\) as \(\Phi\) varies over all isoclinism classes. Given a fixed isoclinism class \(\Phi\), the paper gives asymptotic upper and lower bounds for \(f_ \Phi (p^ m)\) and \(F(p^ m)\) as \(m\to\infty\).