diff --git a/R/type-vctr.R b/R/type-vctr.R
index b2ab8dd8d..72583d055 100644
--- a/R/type-vctr.R
+++ b/R/type-vctr.R
@@ -68,51 +68,12 @@ new_vctr <- function(.data,
                      ...,
                      class = character(),
                      inherit_base_type = NULL) {
-  if (!is_vector(.data)) {
-    abort("`.data` must be a vector type.")
-  }
-
-  if (is_list(.data)) {
-    if (is.data.frame(.data)) {
-      abort("`.data` can't be a data frame.")
-    }
-
-    if (is.null(inherit_base_type)) {
-      inherit_base_type <- TRUE
-    } else if (is_false(inherit_base_type)) {
-      abort("List `.data` must inherit from the base type.")
-    }
-  }
-
-  # Default to `FALSE` in all cases except lists
-  if (is.null(inherit_base_type)) {
-    inherit_base_type <- FALSE
-  }
-
-  names <- names(.data)
-  names <- names_repair_missing(names)
-
-  class <- c(class, "vctrs_vctr", if (inherit_base_type) typeof(.data))
-  attrib <- list(names = names, ..., class = class)
-
-  vec_set_attributes(.data, attrib)
+  .External(vctrs_new_vctr, .data, class, inherit_base_type, ...)
 }
+new_vctr <- fn_inline_formals(new_vctr, "class")
 
 names_repair_missing <- function(x) {
-  if (is.null(x)) {
-    return(x)
-  }
-
-  missing <- vec_equal_na(x)
-
-  if (any(missing)) {
-    # We never want to allow `NA_character_` names to slip through, but
-    # erroring on them has caused issues. Instead, we repair them to the
-    # empty string (#784).
-    x <- vec_assign(x, missing, "")
-  }
-
-  x
+  .Call(vctrs_name_repair_missing, x)
 }
 
 #' @export
diff --git a/man/new_vctr.Rd b/man/new_vctr.Rd
index d3101a8f6..c3a918ef8 100644
--- a/man/new_vctr.Rd
+++ b/man/new_vctr.Rd
@@ -5,7 +5,7 @@
 \alias{vctr}
 \title{vctr (vector) S3 class}
 \usage{
-new_vctr(.data, ..., class = character(), inherit_base_type = NULL)
+new_vctr(.data, ..., class = character(0), inherit_base_type = NULL)
 }
 \arguments{
 \item{.data}{Foundation of class. Must be a vector}
diff --git a/src/decl/type-vctr-decl.h b/src/decl/type-vctr-decl.h
new file mode 100644
index 000000000..7269c9b07
--- /dev/null
+++ b/src/decl/type-vctr-decl.h
@@ -0,0 +1,4 @@
+static r_obj* classes_vctrs_vctr = NULL;
+static r_obj* vec_set_attributes_call = NULL;
+
+static r_obj* names_repair_missing(r_obj* x);
diff --git a/src/init.c b/src/init.c
index 617350fe1..89e4ca087 100644
--- a/src/init.c
+++ b/src/init.c
@@ -138,6 +138,7 @@ extern r_obj* vctrs_integer64_proxy(r_obj*);
 extern r_obj* vctrs_integer64_restore(r_obj*);
 extern r_obj* vctrs_list_drop_empty(r_obj*);
 extern r_obj* vctrs_is_altrep(r_obj* x);
+extern r_obj* vctrs_name_repair_missing(r_obj* x);
 
 
 // Maturing
@@ -296,6 +297,7 @@ static const R_CallMethodDef CallEntries[] = {
   {"vctrs_integer64_restore",          (DL_FUNC) &vctrs_integer64_restore, 1},
   {"vctrs_list_drop_empty",            (DL_FUNC) &vctrs_list_drop_empty, 1},
   {"vctrs_is_altrep",                  (DL_FUNC) &vctrs_is_altrep, 1},
+  {"vctrs_name_repair_missing",        (DL_FUNC) &vctrs_name_repair_missing, 1},
   {NULL, NULL, 0}
 };
 
@@ -309,6 +311,7 @@ extern SEXP vctrs_rbind(SEXP, SEXP, SEXP, SEXP);
 extern SEXP vctrs_cbind(SEXP, SEXP, SEXP, SEXP);
 extern SEXP vctrs_c(SEXP, SEXP, SEXP, SEXP);
 extern SEXP vctrs_new_data_frame(SEXP);
+extern SEXP vctrs_new_vctr(SEXP);
 
 static const R_ExternalMethodDef ExtEntries[] = {
   {"vctrs_type_common",                (DL_FUNC) &vctrs_type_common, 1},
@@ -321,6 +324,7 @@ static const R_ExternalMethodDef ExtEntries[] = {
   {"vctrs_cbind",                      (DL_FUNC) &vctrs_cbind, 3},
   {"vctrs_c",                          (DL_FUNC) &vctrs_c, 3},
   {"vctrs_new_data_frame",             (DL_FUNC) &vctrs_new_data_frame, -1},
+  {"vctrs_new_vctr",                   (DL_FUNC) &vctrs_new_vctr, -1},
   {NULL, NULL, 0}
 };
 
@@ -367,6 +371,7 @@ void vctrs_init_type(SEXP ns);
 void vctrs_init_type_data_frame(SEXP ns);
 void vctrs_init_type_date_time(SEXP ns);
 void vctrs_init_type_info(SEXP ns);
+void vctrs_init_type_vctr(r_obj* ns);
 void vctrs_init_unspecified(SEXP ns);
 void vctrs_init_utils(SEXP ns);
 
@@ -390,6 +395,7 @@ SEXP vctrs_init_library(SEXP ns) {
   vctrs_init_type_data_frame(ns);
   vctrs_init_type_date_time(ns);
   vctrs_init_type_info(ns);
+  vctrs_init_type_vctr(ns);
   vctrs_init_unspecified(ns);
   vctrs_init_utils(ns);
   return R_NilValue;
diff --git a/src/type-vctr.c b/src/type-vctr.c
new file mode 100644
index 000000000..668bb2f76
--- /dev/null
+++ b/src/type-vctr.c
@@ -0,0 +1,188 @@
+#include "type-vctr.h"
+#include "vctrs.h"
+#include "utils.h"
+
+#include "decl/type-vctr-decl.h"
+
+// [[ register(external = TRUE) ]]
+r_obj* vctrs_new_vctr(r_obj* args) {
+  args = r_node_cdr(args);
+
+  r_obj* data = r_node_car(args); args = r_node_cdr(args);
+  r_obj* cls = r_node_car(args); args = r_node_cdr(args);
+  r_obj* inherit_base_type = r_node_car(args); args = r_node_cdr(args);
+  r_obj* attributes = args;
+
+  return new_vctr(
+    data,
+    cls,
+    inherit_base_type,
+    attributes
+  );
+}
+
+// [[ include("type-vctr.h") ]]
+r_obj* new_vctr(r_obj* data,
+                r_obj* cls,
+                r_obj* inherit_base_type,
+                r_obj* attributes) {
+  if (!r_is_vector(data)) {
+    r_abort("`.data` must be a vector type.");
+  }
+  if (r_typeof(cls) != R_TYPE_character) {
+    r_abort("`class` must be a character vector.");
+  }
+  if ((inherit_base_type != r_null) && !r_is_bool(inherit_base_type)) {
+    r_abort("`inherit_base_type` must be `NULL` or a single `TRUE` or `FALSE`.");
+  }
+
+  const enum r_type type_attributes = r_typeof(attributes);
+
+  if (type_attributes != R_TYPE_pairlist && type_attributes != R_TYPE_null) {
+    r_stop_internal("new_vctr", "`attributes` must be a pairlist or `NULL`.");
+  }
+
+  const enum r_type type = r_typeof(data);
+
+  if (type == R_TYPE_list && r_inherits(data, "data.frame")) {
+    r_abort("`.data` can't be a data frame.");
+  }
+
+  bool c_inherit_base_type = false;
+
+  if (type == R_TYPE_list) {
+    if (inherit_base_type == r_null) {
+      // List types always inherit the base type
+      c_inherit_base_type = true;
+    } else {
+      c_inherit_base_type = r_lgl_get(inherit_base_type, 0);
+
+      if (!c_inherit_base_type) {
+        r_abort("List `.data` must inherit from the base type.");
+      }
+    }
+  } else {
+    if (inherit_base_type == r_null) {
+      c_inherit_base_type = false;
+    } else {
+      c_inherit_base_type = r_lgl_get(inherit_base_type, 0);
+    }
+  }
+
+  bool has_names_in_attributes = false;
+
+  for (r_obj* node = attributes; node != R_NilValue; node = r_node_cdr(node)) {
+    r_obj* tag = r_node_tag(node);
+
+    if (tag == R_ClassSymbol) {
+      // Check for this in case we ever allow dynamic dots
+      r_abort("Can't supply `class` in `...`.");
+    }
+
+    if (tag == R_NamesSymbol) {
+      has_names_in_attributes = true;
+    }
+  }
+
+  r_keep_t pi;
+  KEEP_HERE(attributes, &pi);
+
+  if (!has_names_in_attributes) {
+    // Take names from `data` if `attributes` doesn't have any
+    r_obj* names = KEEP(r_names(data));
+    names = KEEP(names_repair_missing(names));
+
+    if (names != r_null) {
+      attributes = r_new_node3(names, attributes, R_NamesSymbol);
+      KEEP_AT(attributes, pi);
+    }
+
+    FREE(2);
+  }
+
+  cls = KEEP(chr_c(cls, classes_vctrs_vctr));
+
+  if (c_inherit_base_type) {
+    r_obj* base_type = KEEP(r_type_as_character(type));
+    cls = chr_c(cls, base_type);
+    FREE(1);
+  }
+  KEEP(cls);
+
+  attributes = r_new_node3(cls, attributes, R_ClassSymbol);
+  KEEP_AT(attributes, pi);
+
+  // Required conversion to VECSXP for `attributes<-`
+  attributes = KEEP(Rf_PairToVectorList(attributes));
+
+  // We don't have access to `Rf_shallow_duplicate_attr()`, which can create
+  // an ALTREP wrapper cheaply, but `vec_set_attributes()` does through
+  // `attributes<-`
+  r_obj* out = r_eval_with_xy(
+    vec_set_attributes_call,
+    data,
+    attributes,
+    vctrs_ns_env
+  );
+
+  FREE(4);
+  return out;
+}
+
+
+// [[ register() ]]
+r_obj* vctrs_name_repair_missing(r_obj* x) {
+  return names_repair_missing(x);
+}
+
+static
+r_obj* names_repair_missing(r_obj* x) {
+  // We never want to allow `NA_character_` names to slip through, but
+  // erroring on them has caused issues. Instead, we repair them to the
+  // empty string (#784).
+
+  if (x == r_null) {
+    return x;
+  }
+
+  if (r_typeof(x) != R_TYPE_character) {
+    r_abort("`x` must be a character vector of names.");
+  }
+
+  const r_ssize size = r_length(x);
+  r_obj* const* v_x = r_chr_cbegin(x);
+
+  r_ssize i = 0;
+  bool any_missing = false;
+
+  for (; i < size; ++i) {
+    if (v_x[i] == r_globals.na_str) {
+      any_missing = true;
+      break;
+    }
+  }
+
+  if (!any_missing) {
+    return x;
+  }
+
+  r_obj* out = KEEP(r_clone(x));
+
+  for (; i < size; ++i) {
+    if (v_x[i] == r_globals.na_str) {
+      r_chr_poke(out, i, strings_empty);
+    }
+  }
+
+  FREE(1);
+  return out;
+}
+
+
+void vctrs_init_type_vctr(r_obj* ns) {
+  classes_vctrs_vctr = r_new_shared_vector(R_TYPE_character, 1);
+  r_chr_poke(classes_vctrs_vctr, 0, r_str("vctrs_vctr"));
+
+  vec_set_attributes_call = r_parse("vec_set_attributes(x, y)");
+  r_preserve(vec_set_attributes_call);
+}
diff --git a/src/type-vctr.h b/src/type-vctr.h
new file mode 100644
index 000000000..ef99a6563
--- /dev/null
+++ b/src/type-vctr.h
@@ -0,0 +1,11 @@
+#ifndef VCTRS_TYPE_VCTR_H
+#define VCTRS_TYPE_VCTR_H
+
+#include <rlang.h>
+
+r_obj* new_vctr(r_obj* data,
+                r_obj* cls,
+                r_obj* inherit_base_type,
+                r_obj* attributes);
+
+#endif
diff --git a/src/utils.h b/src/utils.h
index fcfdcf323..8183b4bbf 100644
--- a/src/utils.h
+++ b/src/utils.h
@@ -270,6 +270,22 @@ SEXP r_new_environment(SEXP parent) {
   return env;
 }
 
+static inline
+bool r_is_vector(r_obj* x) {
+  switch(r_typeof(x)) {
+  case R_TYPE_logical:
+  case R_TYPE_integer:
+  case R_TYPE_double:
+  case R_TYPE_complex:
+  case R_TYPE_character:
+  case R_TYPE_raw:
+  case R_TYPE_list:
+    return true;
+  default:
+    return false;
+  }
+}
+
 SEXP r_protect(SEXP x);
 bool r_is_number(SEXP x);
 bool r_is_positive_number(SEXP x);
@@ -398,6 +414,8 @@ void c_print_backtrace();
 
 SEXP chr_c(SEXP x, SEXP y);
 
+SEXP r_new_shared_vector(SEXPTYPE type, R_len_t n);
+
 
 extern SEXP vctrs_ns_env;
 extern SEXP vctrs_shared_empty_str;
diff --git a/tests/testthat/_snaps/type-vctr.md b/tests/testthat/_snaps/type-vctr.md
index c5a8190f5..b66c5334b 100644
--- a/tests/testthat/_snaps/type-vctr.md
+++ b/tests/testthat/_snaps/type-vctr.md
@@ -1,3 +1,29 @@
+# `class` must be a character vector
+
+    Code
+      (expect_error(new_vctr(1, class = 1)))
+    Output
+      <error/rlang_error>
+      Error: `class` must be a character vector.
+
+# `inherit_base_type` is validated
+
+    Code
+      (expect_error(new_vctr(1, inherit_base_type = 1)))
+    Output
+      <error/rlang_error>
+      Error: `inherit_base_type` must be `NULL` or a single `TRUE` or `FALSE`.
+    Code
+      (expect_error(new_vctr(1, inherit_base_type = NA)))
+    Output
+      <error/rlang_error>
+      Error: `inherit_base_type` must be `NULL` or a single `TRUE` or `FALSE`.
+    Code
+      (expect_error(new_vctr(1, inherit_base_type = c(TRUE, FALSE))))
+    Output
+      <error/rlang_error>
+      Error: `inherit_base_type` must be `NULL` or a single `TRUE` or `FALSE`.
+
 # na.fail() works
 
     Code
diff --git a/tests/testthat/test-type-vctr.R b/tests/testthat/test-type-vctr.R
index 56a7e05da..32706b256 100644
--- a/tests/testthat/test-type-vctr.R
+++ b/tests/testthat/test-type-vctr.R
@@ -11,6 +11,26 @@ test_that(".data must be a vector", {
   expect_error(new_vctr(mean), "vector type")
 })
 
+test_that("`class` must be a character vector", {
+  expect_snapshot((expect_error(new_vctr(1, class = 1))))
+})
+
+test_that("`inherit_base_type` is validated", {
+  expect_snapshot({
+    (expect_error(new_vctr(1, inherit_base_type = 1)))
+    (expect_error(new_vctr(1, inherit_base_type = NA)))
+    (expect_error(new_vctr(1, inherit_base_type = c(TRUE, FALSE))))
+  })
+})
+
+test_that("names come from `.data`", {
+  expect_named(new_vctr(structure(1, names = "x")), "x")
+})
+
+test_that("names provided through `...` override those in `.data`", {
+  expect_named(new_vctr(structure(1, names = "x"), names = "y"), "y")
+})
+
 test_that("attributes other than names are ignored", {
   out <- new_vctr(structure(1, a = 1))
   expect_null(attributes(out)$a)
@@ -32,6 +52,15 @@ test_that("Can opt out of base type", {
   expect_s3_class(x, c("x", "vctrs_vctr"), exact = TRUE)
 })
 
+test_that("base type is correct for atomic types", {
+  expect_s3_class(new_vctr(logical(), inherit_base_type = TRUE), "logical")
+  expect_s3_class(new_vctr(integer(), inherit_base_type = TRUE), "integer")
+  expect_s3_class(new_vctr(double(), inherit_base_type = TRUE), "double")
+  expect_s3_class(new_vctr(character(), inherit_base_type = TRUE), "character")
+  expect_s3_class(new_vctr(raw(), inherit_base_type = TRUE), "raw")
+  expect_s3_class(new_vctr(complex(), inherit_base_type = TRUE), "complex")
+})
+
 test_that("base type is always set for lists", {
   expect_s3_class(new_vctr(list()), "list")
 })