All participants will receive just-in-time adaptive interventions when their personalized model identifies that they are at risk for an eating disorder behavior. The content of the just-in-time adaptive intervention (i.e., the therapy skill targeted) will be randomized at the point of just-in-time adaptive intervention delivery.

Participants will use a smartphone-based program designed to support eating disorder recovery in daily life. Participants will complete brief surveys about their mood, thoughts, and behaviors, and the smartphone will also passively collect activity-related data. This information is used to detect times when a person may be at higher risk for eating disorder behaviors. Participants will watch 4 video modules that introduce the core enhanced cognitive-behavioral therapy skills for eating disorders (reducing dietary restraint, urge management, emotion regulation, and improving body image), provide rationale, and prompt participants to complete interactive activities to practice these skills. Participants will then receive micro-randomized JITAIs prompting them to use these skills in their daily lives; micro-randomization will be used to deliver a JITAI from one of the 4 skill categories (reducing dietary restraint, urge management, emotion regulation, improving body image) or no JITAI.

Performance of the eating disorder behavior prediction models will be evaluated by computing the area under the receiver operating curve (AUC) for each participants' models on two-weeks of held out (test) data (collected during weeks 5 and 6 of the data collection procedure). The AUC can take on values between 0 and 1, with higher values indicating superior model performance.

Performance of the eating disorder behavior prediction models will be evaluated by computing the Brier score for each participants' models on two-weeks of held out (test) data (collected during weeks 5 and 6 of the data collection procedure). The Brier score can range from 0 to 1 with lower values indicating less model error (i.e., better model performance).

Binge eating occurrence during the data collection protocol will be measured. Binge eating at each ecological momentary assessment survey will be assessed by the question, "Thinking about your most recent eating episode, did you experience loss of control?" (Answer choices = Yes or No).

Dietary restriction will be measured during the data collection protocol. Dietary restriction will be assessed at each ecological momentary assessment survey by the questions, "Thinking about your most recent eating episode, did you limit the amount of food you ate to influence your shape?", "Thinking about your most recent eating episode, did you exclude specific foods to influence your shape or weight?", and Since the last survey, have you skipped a meal or snack?" (Answer Choices = Yes or No).

Body image concerns will be measured as a possible mediator of the effect of JITAIs on eating disorder behaviors. Body image concerns will be quantified as the mean rating across the body image items on the Eating Disorder Examination Questionnaire-Short Form, adapted to be rated on a five-point Likert scale as follows: 0=Very slightly/not at all 1 = A little 2 =Moderately 3 = Quite a bit 4= Extremely. Higher mean ratings indicate great body image concerns. Minimum mean score on the items is 0 and maximum is 4.