diff --git a/R/revealjs_presentation.R b/R/revealjs_presentation.R
index 7d8c082..8d1c9d8 100644
--- a/R/revealjs_presentation.R
+++ b/R/revealjs_presentation.R
@@ -198,6 +198,12 @@
   }
 
   # transition
+  if (missing(transition) && identical(theme, "ids")) {
+    # IDS theme: slide the slides in instead of rotating them (reveal.js'
+    # own default, convex), unless the user explicitly asked for something
+    # else. The formal default has to stay "convex" for the other themes.
+    transition <- "slide"
+  }
   transition <- match.arg(transition, revealjs_transitions())
   if (identical(transition, "default")) {
     # revealjs default is convex