diff --git a/NAMESPACE b/NAMESPACE
index 98d11f4..c6bcdd4 100644
--- a/NAMESPACE
+++ b/NAMESPACE
@@ -5,6 +5,7 @@ S3method(arrange_,tbl_json)
 S3method(as.tbl_json,character)
 S3method(as.tbl_json,tbl_json)
 S3method(filter_,tbl_json)
+S3method(mutate_,tbl_json)
 export(append_values_logical)
 export(append_values_number)
 export(append_values_string)
diff --git a/R/data-companies.r b/R/data-companies.r
index 8fc6482..158f280 100644
--- a/R/data-companies.r
+++ b/R/data-companies.r
@@ -19,6 +19,9 @@
 #'   spread_values(
 #'     name = jstring("name")
 #'   ) %>% 
+#'   mutate(
+#'     company.sort_order = rank(name)
+#'   ) %>%
 #'   enter_object("relationships") %>%
 #'   gather_array("relationship.index") %>%
 #'   spread_values(
@@ -46,4 +49,4 @@
 #' ggplot(comp_type_counts, aes(key, n, fill = type)) + 
 #'   geom_bar(position = "stack", stat = "identity") +
 #'   coord_flip()
-NULL
\ No newline at end of file
+NULL
diff --git a/R/tbl_json.r b/R/tbl_json.r
index c957234..2b83021 100644
--- a/R/tbl_json.r
+++ b/R/tbl_json.r
@@ -125,3 +125,6 @@ filter_.tbl_json <- wrap_dplyr_verb(dplyr::filter_)
 
 #' @export
 arrange_.tbl_json <- wrap_dplyr_verb(dplyr::arrange_)
+
+#' @export
+mutate_.tbl_json <- wrap_dplyr_verb(dplyr::mutate_)
diff --git a/man/companies.Rd b/man/companies.Rd
index 00c8895..93f5354 100644
--- a/man/companies.Rd
+++ b/man/companies.Rd
@@ -23,6 +23,9 @@ key_employees <- companies \%>\%
   spread_values(
     name = jstring("name")
   ) \%>\%
+  mutate(
+    company.sort_order = rank(name)
+  ) \%>\%
   enter_object("relationships") \%>\%
   gather_array("relationship.index") \%>\%
   spread_values(
diff --git a/tests/testthat/test-tbl_json.r b/tests/testthat/test-tbl_json.r
index fb67db0..63fa75c 100644
--- a/tests/testthat/test-tbl_json.r
+++ b/tests/testthat/test-tbl_json.r
@@ -163,3 +163,31 @@ test_that("dplyr::arrange works with a simple example", {
     
   }
 )
+
+
+test_that("dplyr::mutate works with a simple example", {
+    
+    x <- as.tbl_json(c('{"name": "bob"}', '{"name": "susan"}'))
+
+    result <- x %>%
+      spread_values(name = jstring("name")) %>%
+      mutate(
+        name = factor(name),
+        newcol = c(4,5),
+        fullname = factor(paste(name, "green"))
+      )
+    
+    expect_identical(
+      result,
+      tbl_json(
+        data.frame(
+          document.id = c(1L, 2L),
+          name = c("bob", "susan"),
+          newcol = c(4, 5),
+          fullname = c("bob green", "susan green")),
+        list(list(name = "bob"), list(name = "susan"))
+      )
+    )
+    
+  }
+)